nice beaches in ghana

Busua in the west is probably the best beach in Ghana--safe swimming and several hotels of different price and quality are available. Also has to be about the cleanest beach I've seen in a fishing village.

Kokrobite is near Accra and has a decent beach with a bit of a rasta vibe if that is your speed (it's not mine).

A good beach/nightlife combination is pretty hard to find in Ghana as the best beaches are usually by small towns. Accra of course has the best nightlife but frankly I don't like any beach there (except maybe Coco Beach in Nungua). Labadi Beach is the most well-known but I personally don't like it that much, though it is a place you can hang out in the evening with quite a few other people there on the weekend. I won't swim at any beach in Accra because of the filth--and I'm not a picky swimmer!

Agree with Mr. Taharqa, you cannot find nice beach with good night life at the same time.
Some kind of night life (sitting in the bar, listening to music and drinking star) has Busua (Alaska bar), Kokrobite (Big Millys) and Labadi Beach (probably the best night life but not for swimming).
Concerning night life only (clubs, discos), you will find it just in Accra or Tema. For the best night life come to Abidjan, CI.