Another suggestion is to spend the evening at the BoardWalk Resort. It has a few restaurants, clubs and shops and isn't quite as nutty as PI often is. Much depends on your age, club going habits and your arrival day too.
On weekends, PI and CityWalk attract many 20-something club goers from the local area. It can get rather wild on some nights. During the week there are more tourists and families. Both PI and CityWalk have places to dance to a wide variety of music (latin, techno, top 40, oldies, R&B, etc.). PI also has a jazz club, performance (Adventurers Club) and comedy club.
BoardWalk is a more relaxed place but still offers it's share of entertainment. They have the ESPN Club, Jellyrolls and Atlantic Dance. Dine at Flying Fish, Spoodles, Big River Grill and Brewing Works or the ESPN Club. Don't forget the bakery for a late night treat. You can even grab a slice of pizza and eat by the water if you choose.