Thanks, Christian,
I had considered that, as you are right about the overlap between the 5mm and 2.5mm. I just have a hard time believing I could make much use of a 7mm, as most of my "dream dive destinations are probably going to be 70f and up. By dream dives - I mean Bonaire, Papua New Guinea, Fiji, Galapagos (maybe a little colder), Thailand, Indonesia... unless some local from NYC told me there was GREAT diving with tons to see around here (maybe there are - I just don't know), I can't picture myself traveling to too many cold water spots over a tropical destination.
I do remember doing my OW dives in a 7mm farmer john combo - that was THICK!!!
My experience so far has suggested that I don't get cold too easily, so I figure the 5mm would be good for at least down to 65. And I could always buy a hooded vest or something if it got too cold. On the flip side, it seems the gap between 7mm and 2.5mm is a bit wide... I will think about it, though. Thanks again!