We returned from Kaanapali a couple of weeks ago. It was spectacular! We’ve also been to Wailea several times - my daughter got married there. When in Wailea, we’d go to Kihei for restaurants and shopping. It’s a laid back town with a local vibe.
If beaches are your thing, you’re heading to the right place! The entire island has phenomenal beaches, especially the west side where Kihei is located. If you’re into hiking, there are great trails to the north and of course, there’s Haleakala National Park, which is up around 10,000 feet and an entirely separate climate. While you can go on a snorkeling tour boat, personally, I’d save the money because there is fantastic snorkeling just off of several beaches. The only exception to this for me is the Trilogy Lanai sailing tour because the catamaran ride is a blast and they have exclusive access to a beautiful beach on Lanai. Black Rock Beach up in the Kaanapali area has sea turtles in knee deep water - no snorkel required! Plus, there’s a great cliff jump there. The water is a deep blue out in the jump area - something you have to see to appreciate. Last, I’ve done the road to Hana a couple of times and never enjoyed it that much, based on how long it takes. It’s a full day and most of that day is behind the wheel in traffic. A tour might have been more enjoyable, but as the driver, I didn’t particularly like it. Yes, there are beautiful stops along the way, but because we were trying to do the whole thing, we never had very much time any any one stop. And parking was very limited at these stops, from what I recall. YMMV.
Enjoy your trip - it will be an absolute blast!