I originally was after a S14 but opted out due to me not being able to fit comfortably in one. I'm around 6". Having said that, the S14 had a sunroof which was probably the issue, however they still feel quite cramped, i'd hate to have a crash in one....
The R33 is nice and comfortable to sit in, more room up front as ppl say (the back is still useless). I've heard that the S15 has a "cheap" interior which rattles to shit, and that the 6sp box isn't that great.