I have heard from a few people that have attended launches that you can get in line and purchase a new LTT if the launch is scrubbed after they have boarded a bus. I am not sure on the Florida Dolphin Tours procedure but I will be asking when I board the bus on the 14th. What I don't know is that if people who already had LTT were given first crack at the next launch LTT or if those at the VC also have a shot at them.
People posted in this thread that people at VC can also buy LTT tickets for the next launch attempt and they have even better chances because KSC starts to sell ticket almost right away.
About Florida Dolphin Tours procedure I think that it works in the following way: In some very special rare circumstances (I do not know which ones) KSC will not offer LTT tickets for the next launch attempt to anyone. Otherwise everyone (including those who are with bus tours) on KSC grounds gets a chance to buy an LTT ticket for for the next launch attempt. From what I spoke with Florida Dolphin Tour - they will provide the transportation for the next attempt to VC and if KSC will offer LTT tickets, to NASA Causeway.
So I think that we are in equal conditions here with whose who got direct LTT tickets. 
I have to admit, that I've never attended a launch but if I'm thinking about the process this is what's going on in my mind:
Best chances of getting new LTTs in case of a scrub is for those
who are at VC at time of announcement of the scrub.
If you didn't enter the bus to the causeway, you didn't loose your LTT and as far as I understood my travel agency (Gator) my LTT isn't lost.
But everybody will try to get new LTTs - even if his own one is still valid - to be on the safe side for former launch attempts (or even only to make money with reselling). So it's the question if there are any LTTs left to buy, if you've been on the bus - or right there at the causeway.
(or do they sell new LTTs
at the causeway?)
For the people travelling with a tour bus there will be an additional problem. Will they return to VC after the scrub from the causeway or not? (my little help for this problem might be an additional VC-Ticket with PP I own - but as quoted in other comments this will not work).
So my strategy will be:
Using the LTT from gator on the first attempt and praying.
If I left VC to go to causeway and scrub will be announced:
hoping for new LTTs from Gator.
If this doesn't work;
Use the VC-Ticket for the next attempt (with a bit of hoping for scrub).
In the case of scrub: Running to the ticket booth as fast as I can
buying 1, 2, 3... LTTs to be on the safe side for all later attempts.
That's all I can do.
Do you think this a good strategy?