Ha, in Greenville, we have one gay bar. I suppose that would make it more inviting, except that its a private club and not very good. huzzah for the south...
I've visited Dallas, it seemed alright, though everyone is kinda shoved into Oaklawn.
SanFrancisco, while very open with its gays, was, for me, very rough. I think it was partly me not prepared for how very gay it was (coming from SC and all) and that there were tons of really beautiful people there who basically ignored me. I met a couple cool people there, but it was intimidating. Next time I go, I think it'll be much better.
Phoenix, I visited, but didn't really get into the scene, didn't have anyone to go with, and i hate to go to bars and stuff by myself.