The problem you're facing is that the crater and Hell Diver are in Maui and the manta dive is on the Big Island. There's a "manta cleaning station" on Maui, but it isn't reliable for mantas like the Big Island and nobody that I'm aware of does a regularly scheduled dive there.
Recommending where to stay will depend on a few things. How experienced of an ocean boat diver are you? Do you want to shore dive or boat dive, or a combination of the two? Do you mind driving 45 minutes to catch your boat? What does your wife want to do? Does she want to hang by the pool, be on the beach, go shopping...?
My 2 cents:
Kaanapali is a fantastic area to stay when you're looking for a beach front resort experience where you don't have to drive everywhere. Can be expensive depending on the time of year, where you stay, etc. You can eat (and drink) and an enormous variety of restaurants, and enjoy an upscale shopping area all within a short walking distance from your resort. You're also a 10 minute drive from Lahaina with all it has to offer. You have a choice of two dive operators, one geared toward the vacation type diver who doesn't do the Hell Diver, but they do dive the Carthaginian on a weekly basis. The other operator mostly goes to Lanai, so no Hell Diver and no Molokini.
Kihei is more of a spread out, locals type of town and would be considered most affordable The vast majority of condos are across the street from the ocean and there would be a limited amount of restaurants within walking distance so you wind up driving more. However, you have a great choice of excellent dive operators who depart out of the Kihei Boat Ramp or Maalaea Harbor (Ed Robinsons, Mike Severns, Makena Coast Charters, Dive & Sea, B&B, The Maui Diamond, Pro Diver, etc.). Ed Robinsons typically dives the Hell Diver (conditions permitting) on Ed's Wednesday charter. The Maui Diamond schedules the Hell Diver a couple of times a month, but you'd have to check with their website or Maui Dreams to find out the schedule. All of the operators pretty much start their dives at Molokini, with some doing the back wall regularly.
Wailea/Makena is upscale (translate: expensive) and similar to Kihei as far as driving to eat, etc is concerned. The resorts are beach front with lots of amenities. Parking can be $25/day at your resort if that tells you anything. You can walk between the resorts for meals, and there's a very upscale shopping mall nearby. Once again, you'd catch your boat charter at the Kihei Boat Ramp.
There's shore diving all up and down the coast, and you can find places with super easy entries. You can find shore dive guides easily like Maui Dreams and Shaka Doug to name two. Regardless you will definitely want a rental car.
Give us a bit more specific information about what you want and we'll try to help you dial it in a bit more.
