I wrote up some tips for a friend who will be on the Causeway for his first ever Shuttle launch and decided to post them here also, I hope they are helpful.
What to bring: No more than one backpack of stuff, make sure it's organized for easy security screening. I find chairs unnecessary, if you really hate sitting on sand or grass, bring a poncho or something similar. Bring your camera, longest lens, a wide lens (for time spent at the Visitor Center) and a minimum of other accessories (cleaning supplies, spare memory cards, spare batteries, no flash, no other lenses, no tripods, etc). BRING FOOD! It's true that you can buy food both at the Visitor Center (crowded, huge lines, and overpriced) and at the Causeway (limited selection, and it means risking giving up your spot), but you want to pack as if you can't. This doesn't mean bring a cooler and tons of "real" food, I've found I can survive quite a long and active day on nothing more than two boxes of animal crackers and a water bottle (bring it empty, fill it at the Visitor Center from a water fountain). Also bring one or two "porta potty packs", these are toilet paper, a paper towel or two, and a couple of antibacterial hand wipes tucked into a small discreet bag that you can keep on you, this way you won't have to worry about finding a properly stocked one. Finally, if you have one, bring a battery for your iPhone, you'll be relying on 3G the whole day, so it'll be sucking down a lotta power if you don't exercise discipline with it (aka, keep it turned off most of the day). Other essentials: bug spray (I recommend Coleman SkinSmart Deet Free, it's been proven to work really well on most FL pests), sunscreen (as high an SPF as you can wear), and a poncho or compact umbrella plus a waterproof cover for your backpack (unless your poncho can cover you AND your backpack). Bring at least one poncho regardless of the weather forecast... on the coast rain can come out of nowhere, especially in the afternoon. And yes, if it's raining, NASA will still try to launch, so you'll be stuck standing out there on the Causeway where there is zero cover. DO NOT bother with a waterproof cover for your camera itself... if it's raining, keep it packed, you wouldn't get any good shots anyway even if she launches. Oh!!! And bring small bills or change in quarters so you can rent a locker at the Visitor Center, you'll need to if you want to ride the Shuttle Launch Experience (which you should).
What to do: Get to the pickup location EARLY... thirty minutes to an hour before their recommended time is fine. Ask questions... never get into any line if you haven't asked someone in a uniform (or sometimes two or three people) what the line is for (unless you can see the other end). Once on the bus, take a nap until you get near the coast, then keep your eyes open for a glimpse of the pad or the VAB out the left-hand side of the bus (oh yea, try for a left-hand window seat on the bus going out and a right-hand window seat coming back, if you can). Once at the Visitor Center, security is basically like an airline, keep your tickets put away but accessible, sometimes they screen before you enter, sometimes they screen as you enter, so be prepared for both. Bathrooms are plentiful but hidden, pick up a tourist map as the Visitor Center can be a bit of a maze. I highly recommend checking out an Imax if you can while you're there, the Hubble in 3D is quite good. But the first thing I recommend you do on arriving is head over to the Shuttle Launch Experience and ride that at least once, it's amazing and well worth the wait for a locker and the wait for the ride itself. Now just enjoy the rest of however much time you have at the VC, there's lots of cool stuff to see and do, I recommend swinging by the Memorial but be prepared to get a little misty-eyed if you read the inscriptions there. And of course climb up into the crew compartment of the Shuttle mockup they have there. The line to get on the buses to the Causeway will start early and fill up fast, I've seen it run 3/4 of the way around the perimeter of the Visitor Center, and it tends to be very disorganized. Rule #1 do NOT get stressed out about it! Every single bus has to wait for the very last person in that line to board before any of them can head to the Causeway, so where you are in line, who butts in front of you, or when you decide to get into the line really don't matter. Enjoy the VC for as long as you feel comfortable, even if the line has already started moving you've probably got another 30 minutes before you really HAVE to get in line and go get on your bus. But don't think they'll hold the buses up for you or you may end up watching the launch from the Visitor Center with no ride home!
The Causeway: The view from the Causeway is fantastic pretty much everywhere, but there are some tips. Avoid the little low islands between you and the pad, there are a few places where you can line things up so it's nothing but water from you to the far shore, so try to find one of those spots early and grab it. Also, I recommend staying up high, right against the buses, rather than slugging it out down in the weeds with all the tripod-toters. The way the ground slopes I've never had anyone who was standing in front of me get in my shot, and if I'm safe at 5'2" then you will definitely have a clear shot also. Up high the ground is drier, there are fewer bugs, and it's less crowded. I recommend finding your spot in less than 10 minutes after getting off the bus, if you were paying attention during the drive out to the Causeway you should know what direction to walk and how far to find a clear spot between islands. Once you have your spot, spread your stuff out around you as much as possible (throw your poncho one way, your backpack the other, stand between). Over the next 30-45 minutes pretty much everyone will settle on a spot, and that means you'll have neighbors. Get to know them, be friendly, be helpful... these are the people who will be saving your spot when you have to go use the porta potty or grab some food or drink. The people who attend Shuttle launches are just like an airshow crowd, aka awesome. Now it's just a matter of waiting. Keep alert, there should be speakers following along with launch preparations, and there will be aircraft in the air (Hueys, F-15s, KC-135s, T-38s, and of course the STA or Shuttle Training Aircraft) plus all sorts of wildlife (you'll certainly see Herons, Pelicans, Ospreys, and Dolphins). Just make sure you keep one whole memory card and one fresh battery in reserve just for the launch, you'll want 'em. During the T-9 minute hold pack up your things and be ready to shoot and then move, they get you back on the buses ASAP. Also, psych yourself up. Especially once they get past the T-9 minute hold, if your hands aren't literally shaking, you aren't doing it right. You're about to see 4 human beings sitting on top of a nuclear bomb's worth of energy go from zero to 17,500mph in about 6 minutes. This is frakking awesome, and you are going to FEEL the power of that rocket, I mean it's going to literally punch you in the stomach, repeatedly, just to make sure you get the point about how awesome this is. Get excited!
The launch: It's over and done with far too quickly. I'm praying for a clear blue sky because if there is cloud cover then it'll be over and done with even quicker (like STS-134... 20 seconds from ignition to out of sight). The Shuttle will climb up and then bend to the right very quickly, so be ready to track it. Here is what I recommend as far as camera vs experiencing it. Have the camera poised and ready to go, catch the engine ignition, initial smoke, and then the Shuttle emerging from the smoke with your camera. Once you can no longer see the Shuttle and the Pad together without zooming out, put the camera down and watch it for a little while. Snap another couple of shots if it looks pretty, but soon the sound should reach you, and when it does put down the camera for sure and just feel the shock waves of the thing while watching it go. Keep an ear on the radio broadcast, it is literally unbelievable how quickly they accelerate and get downrange, you'll be looking at this flaming spec hurtling away from you thinking "that's cool" and then the guy on the radio will say something like "T plus 25 seconds Atlantis and her crew are now XXX miles downrange traveling XXXX miles per hour", and then you'll be like "holy fuck that's impossible!" For the rest of the launch keep it in view as much as possible, once the sound waves have passed pick up your camera again and use its lens to try to spot SRB separation. Don't feel like you have to rush to get on your bus, it'll take them a good 15+ minutes for everyone to find theirs and the first few rows to start leaving, but it may be 30 minutes before your bus leaves. On the way back, check out your photos and relive the experience with your fellow passengers, everyone is going to be riding a huge adrenaline high so enjoy it. Keep an eye on your watch. Exactly 90 minutes after lift-off, Atlantis has already made one full orbit and is back overhead. Just think about that while you're sitting in traffic probably no more than 10 miles from the Causeway... Atlantis, that vehicle you just saw less than two hours ago sitting on the pad 6 miles away from you, has gone completely around the Earth, seen the sun set and rise, and is now looking down at you... while you sit in traffic. Your fellow bus passengers may get a kick out of that also

She'll probably be on Orbit 3 by the time you get back to the drop off location in Orlando.
Well, I hope that helps your day be even more awesome, sorry it ended up being so long, I'm getting pretty darn excited just writing this, I don't know if I can wait another week!