Cabs are cheap, go to the Gold Suk (they will negotiate), Mall of the Emirates (ski slope inside), go to the sister resort of the hotel we stay at for the beach. I went on a desert safari, arranged by the hotel and it was a good way to waste an evening. They pick you up at about 3pm and return you about 10pm (approx). I know the dinner buffet in the Hotel is very good, but you may need reservations unless you go very early or late. There is plenty of nightlife but I am not well schooled on this in DXB.

Hope this helps.