I just got back from two weeks and 40 dives with JADS...yes that means I dived every site on the west side of the island and a good number of those two or three times.
You can't go wrong with JADS, they are a fun group who will take care of you, they also dive the south coast which has a lot of the better dives. Jane Sea, the Airplanes, Fingers, Golden Island, Kantil are all good dives. Santa Largo, Rocky Beach, and Mango Halto are one long reef, if offered a shore dive go for Rocky Beach unless you like walking your gear and long surface swims over shallow reefs. It's certainly not the best diving in the Carribean due to lower vis and more beat up reefs but it's still great diving IMO.
They do the north coast on Thursday, that's where Antilla is. The second dive is typically Debby II which is a decent wreck followed by Blue Reef as a drift (all one dive). If you like looking at scrap metal on the sea floor the Perdenales is for you. There are usually morays and some large porcupine fish in the area though.
Their boat leaves from a dock just south of the Airport so the drive from San Nicholas isn't as bad as the others either, or let Chicha pick you up and drive you there.
Have a blast and tell Urny that Ron sent you~~