Hi - I can't comment on Aarons - it had been recommended to me if I were to stay in Kailua again. But on Oahu - cross island from Kailua - I recommend Ocean Concepts on Makaha coast - awesome group and top notch operation, 2-tank AM boat dives. web: oceanconcepts.com - you can see their schedule. If you do this, definitely get there on a day for the Mahi Shipwreck - incredible! For a south island alternative, people I dove with recommended: Island Divers - web: oahuscubadiving.com. For North Shore, strong recommendations for Deep Ecology - web: deepecologyhawaii.com [the website is a bit annoying though]. Wish I were in Kailua!
Have Fun