Like Dawyg said, Vegas is great. All kinds of action from very small to extremely ridiculous and everything in between, the games are normally very good. Of course, I'm somewhat biased as I've lived in Vegas for 8 years and love it here.
Having said that, there are a lot of great places to play in the US, and around the world for that matter. Poker is popular everywhere.
From a pure $$ aspect, Vegas and Atlantic City are pretty similiar in the action available, except at the very biggest limits.
Los Angeles is the undisputed action and parlay capital of the US. Its not uncommon to see someone playing 4-8 one day, 30-60 a few days later, and then maybe even 100-200, then a week later you see them back at the low limits starting again. Lets just LA players are big time action players and really bring a new meaning to the word "gamble".
Jason