Apparently Mars Odyssey had a DLA of 51.7 degrees: page 14 of http://www.boeing.com/defense-space/space/delta/kits/d284_mars_odyssey.pdf. (Thanks to Jim for pointing out Mars Odyssey's declination in another thread.)
Answering part of my own question, it looks like Mars Odyssey was near the upper end of the range of Mars transfer DLAs. See figure 5 of http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/19062/1/98-0259.pdf and many figures of http://www.scribd.com/doc/33801471/NASA-MSFC-Mission-Design-Handbook .