hey
I live in Caracas at the moment. The best place to go to in terms of beaches is Morrocoy national park I would say. You go by lancha (small boat ) to the various islands.
Caracas has a lot of nice bars and discos. Most popular areas is Mercedes and Altamira. a little upper class but very nice.
If you need to know anything about caracas just write me. I will be going to colombia in december however