US-friendly sites I never had a problem with: WPEX, Poker4ever, Poker.com (now Carbon Poker), Doylesroom. I am non-US and use NETELLER, so the actual cashout process might be less smooth for US.
Bugsy's Club and True Poker also come to mind. Poker World is tied to a massive sportsbook as well and part of the Gold Chip Network which is rather small.