Forgot to add:
Bar's - The Purple Bar above Nonna's in bricktown and the Red Piano Bar at the Skirvin Hotel are the two most popular bars for adults (not college age kids). The Mont is popular in Norman right of campus. Louie's is popular in Norman among adults. Coach's and Bricktown Brewery are very popular with guys for sports, etc. Harry Hudson's is a smoky, pool-hall that is popular. Depends on what you want from it.
As for entertainment, depends on what you are looking for. As for the arts, the Museum of Art is not too bad. There are some good Broadway shows that come to the civic center. Also, look at Rose State, a lot of really great out of town performances are done there. If you like sports, there are soccer leagues in NW OKC, indoor and outdoor. Look at what they are doing on the river too off Bricktown. They have rock climbing, rowing, sailboating, etc. If you are looking for lake activities, your best bet is to go out of town to Grand or Eufala. There is horseriding out at Stanley Draper (not safe place at night).
Go to the Moore Warren Theater is you like movies. You can have balcony seats with drinks and food served for those movies. State Fairgrounds always has activities. Shakespeare in the Park jumps b/t Edmond, Norman, and Botanical Gardens.
If you are looking for something more specific, let me know and I will do what I can. In the meantime, hope this helps some.
Protrident's Rib