FYI - San Nicholas is one of the poorest sections of the island, has the highest crime rate, and is rampant with open prostitution. It definitely was not a place to take your girlfriend/wife.
As previously mentioned, Mambos and Iguana Joes, but the most hopping place is Carlos and Charlies. It is also the place that those little pigs started their death march with Natalie Holloway.
Jeep is the way to go if you are renting. Wath out for the party bus'. They will slam you off the road. Best thing to do with a jeep is explore the desert inland and eastern portions of the island, but be prepared for 2' of trash piled in the coves.
Diving is very poor and uninteresting. Food is good if you like continental cuisine - be forewarned that many of the restaurants require slacks and collared shirts (kinda a huge drag being on vacation). Don't expect to find any distinct culture. Aruba is a mish mash of different folks, and was only populated since the 1920's. Some Aruban's are very friendly, but we found most to be indifferent, with a higher than normal proportion that are just rude (population is overrun with young punks).
Would suggest Bonaire or Curacao as alternatives if you are a serious diver.