Buffalo is right... good suggestions & traffic is going to be a pain during those hours. You may also wanna try:
- Santa Monica Pier
- 3rd Street Promenade (which is near Santa Monica Pier) Restaurants/bars/specialty & exotic shops/theaters/street entertainers, etc.
- Old Town Pasadena (on Colorado Blvd) Restaurant/bars/specialty & exotic shops/theaters/home & clothing shops, etc.
- Long Beach off of Pine Blvd (aka THE PIKE) ... keep going all the way towards the ocean... it's passing Ocean Blvd. Brand new shopping center/entertainment area. There's also a Hooters on Pine Blvd a little north of that shopping ctr. I've only driven by this one so excuse me if I'm wrong: theaters/restaurants/arcade/specialty shops
- Hermosa Beach Pier/Strand - Restaruants/bars/few shops/Beach access/Comedy Magic Club South on Hermosa Ave
- Venice Beach
- Getty Museum - They're open late, parking is $5, admission is free and there are AWESOME views!
- Melrose - Restaurants/bars/specialty & exotic shops/freaks
- Belmont Shore in Long Beach - Restaruants/Bars/specialty shops

You may also wanna try LA Times for more info.

Is there anything specific you want to do?