This may just depend a lot on the kind of music you play or want to play - something that you haven't specified, nor is it mentioned in your profile, as you haven't filled out your profile.
New York is a jazz kind of town, but what I see from Craig's List posts here is a lot of residual metal & punk influence in the rock music. There's the usual classic rock thing - and a bunch of other kinds of things, but in much smaller doses, that you really have to hunt for (like me).
Boston has long had a thriving rock scene. Don't know what kind of shape it's in at present, but it seems more attuned to heady, esoteric forms, such as prog rock and fusion - since it is such a university town.
DC supposedly has (had?) an underground hardcore scene, but I don't know if that still exists. I'm sure there are a quite a few cats gigging in the suburbs (probably playing pretty mainstream fare), but I've lived in DC. DC doesn't impress one as a music kind of place, if you know what I mean.
Philly? No idea.
But I agree: Unless you want to play Southern rock and country music, better get out of (eastern) North Carolina. At the very least move to the Triangle area...
MM