I don't think money's a problem. Skip the shore dives, only because boat dives to molokini and other places are much better. Not economically better, but convenience and time better
I stay at the Grand Wailea myself - I have used Charlie's company, and while he's a very nice guy and runs a nice operation on the grounds, you will be disappointed with the shore diving. It just ain't all that great.
I would HIGHLY recommend B and B scuba -
Maui Hawaii Dive Boat and Scuba Training Center - B&B Scuba to dive with. They board the boat at the Kihei boat ramp literally a mile down the street, the concierge will be able to give you directions very easily. While Ed Robinson's is fine as well, with 25 dives and worried about solo my money would be on Brad and Blesi providing you the most confidence and FUN. They leave wicked early, but they're back early enough for you to grab a smoothie, head to the pool, hook up with the family and have lunch.
And it's worth it to get up and drive to Lahaina to go out with Lahaina Divers to Lanai for the cathedrals - it's potentially a cattle boat, but the divemasters do a good job, the big Newtons are stable crossing the channel to Lanai(I tend to get seasick, and I have three kids with me, so that's who I use), and they're great for beginning to intermediate, especially with no hawaiian dive experience.
THEN, if you want to shore dive, find shaka doug
Another tip: The night dives, if you want to do them, are mostly shore, but Lahaina divers does one trip a week for the night dive. It's worth it too if you haven't done many.
Here's the dives you'd want to do, in my highly opinionated order:
Molokini - just because everybody does it.
Back Wall - it's a great drift, but don't do it first if you're not an advanced diver
Lanai cathedrals - the best diving Maui has to offer, IMHO
Carthaginian wreck - not a super-interesting wreck, but nice nonetheless
Reef's end drift - a stunning drift in which you may see some big pelagics in the blue water. Usually ripping current, just go with the flow and stay with the DM.
Other dives are fill-ins, like five graves, the St. Anthony, mala wharf (although that's a very nice shore dive, just a long way from Wailea), etc. They're very nice, but not top of the list.
If you want any tips on the Grand Wailea, pm me. I've been staying there almost every year for 15 years.