Take this with a grain of salt, as I only just put in my package.
My recruiter was on campus for a career fair, and he had up a sign that said "minimum GPA 3.4" for SNA/SNFO. When I asked about that (he was pushing me towards those, with my 3.0) he said it was because half the people coming up to him were in majors like hotel management and hospitality. At our school, you can sleep through those classes and steal the professors car, and the worst you'd get is a 3.8. (note: you can study round the clock for engineering at the same school and barely pull a 2.5)
From what he told me, the boards always look at the whole person concept. If you have a psychology degree from Harvard it will look a hell of alot better than an Aerospace degree from the local community college.
If you don't know how they'll like it, apply and find out. There is no "one thing" that will get you summarily rejected, with the exception of things that would get you kicked out of the services in general.
