Hmm...
Tempe: Where all the weekly/biweekly Smashfests are. I'm not sure how often you'd be playing here, but every time you did, it'd be a pretty decent smashfest. Active players around here are like, Goop, Wobbles, Light, Dark, a few other barely-active players. I'm not sure what luck you'd get trying to play with any of them outside of a smashfest, but if there WERE a smashfest, it'd be pretty reliable that they go.
Phoenix (Northwest/Central-West specifically): Where I am; I'd be willing to play at least once a week, hopefully twice or thrice depending on my homework and stuff. Around here, there's a few other players too (rugoodat, maXXXpower, and his crew, Vat-Zero, Toro, and Yoko). Unless YOU were busy, you probably wouldn't go a week without smash. Most of Tempe's smashers actually have lives to deal with, which is probably why they don't have smashfests EVERY week; I, on the other hand, am still in high school.