I have 31 dives off Oahu during 3 brief "business" trips, all with Alex Mason, AAA in 2006 and 2008 and Alex's Aquatic Adventures in 2009. All 3 trips are reviewed on Undercurrent. He did a great job ensuring I had good dives and enjoyed myself. The Sea Tiger and YO-257/San Pedro are fun wrecks and the Corsair is certainly worth doing at least once. The reef dives are interesting for a mosly Caribbean diver like me with all the unique and/or endemic fish. I believe Alex will pick you up at your hotel, there's a lot of information on his website and he is responsive by email or phone.
The water is cooler than you might think, consistently lower 70s this time of year. I dived with a 3mm and hooded vest. If I were going today, I would take my 5mm and the hooded vest, especially if doing 4 dives per day. I'm sure many of the operators on Oahu and in Honolulu are very good, if I were to return today, I'd dive with Alex. If you communicate with him, relay my regards.
Good diving, Craig
? Moderator move this to Hawaii forum for better exposure