I'm a firm believer that sex doesn't have to make things awkward, I think I am the kind of social being comfortable enough with myself and others to call it what it is and not let it get in the way of other things.
that being said, i've experienced the spectrum of awkwardness lol but it was always with the same guy, this dude i hooked up with while my current boyfriend and i had broken up. i was in such a messed up place emotionally that i don't think i could even feel awkward if i wanted to. but it would happen that after we hooked up, he'd go like a week without talking to me, and that just didn't work for me. eventually i started to dislike him as a person, which made the SEX awkward for me, so i started to ween off him. he wasn't that good anyway. but he's the kind of guy that has to be in control with the last word. insecure.