Depends. Casinos & drinking are main entertainment. Club in Cesars, Neros, plus a new one in the Horizon.
If your an out-doorsy type, hiking, biking, etc. If not maybe sightseeing (with your car)
Go to Carson city for "full contact adult entertainment."
The lake is nice but cold. There are several beaches around. Launch facilities are limited. If you have a boat go to "the Keys"
Golf in Carson city too. Theres a small course in SLT.
Good Luck. (we might be there Sat night.