Thatch, the base cars are a super bargain, but since they don't come in an automatic, that may be a problem for D.C. traffic.
But at 6'5", to be completely honest with ya, I don't think you're ever going to get comfy in a coupe.
The roadsters have a little more head room (with the top up) than the coupes have, but I think it would still be close.
I know there are a few people on this site that are as tall as you, and they say that they fit. But I'm 6' 2", and I think 6' 3" is about the limit for a coupe.
I really don't know if the cloth seats in the base car offer anymore head room than the leather seats, (they are different). But when I sat in one I thought it felt like it did.
Just keep looking, I'm sure you will be able to find one somewhere to try on for size.
If all else fails, the Honda Civic coupe should accommodate you. While not being anywhere near as much fun to drive as the Crossfire, I got over 40 mpg with mine last week on a trip to Lake Norman N.C. So that may be a trade off you can live with.
Good Luck.