I would say that unless you know you'll be returning to Maui in the future, plan to do things like the road to Hana and Haleakala while you're there. We own a timeshare on Maui, so go at least once a year. Combine that with the fact that we live on the West Coast, and it's a direct flight, it makes Hawaii a very appealing vacation destination for us. Last year we enjoyed our timeshare in August and invited another couple to join us. It was their first trip to Maui and they said many times that it likely would be their only trip as Maui is out of their normal vacation price range.
Because my husband and I go frequently, we often do nothing but dive and hang out, which is what we planned to do on this trip. We planned to dive everyday, but our friends had their own rental car so they weren't bound by our activity choices and could do whatever they wanted. Our friends are a husband and wife team where the wife doesn't dive, and since she was exhausted and just wanted to do nothing the first couple of days, it was perfect for her husband to dive in the mornings and hang out with her in the afternoons. Unfortunately, she set a presidence and once the husband started diving with us every morning, he didn't want to stop.
They wound up with only one day to explore the island and do stuff, and unfortunately that was the one day where we had rain, so going to Haleakala wasn't really an option. When we all got home, she was pretty disappointed that she didn't do the things she wanted (Haleakala, horseback riding, parasailing...), but at least felt rested and healthy, which was a positive outcome of the trip.
Fortunately for them, we really had a great time together and found that we're an extremely compatible 4-some for travel, so we invited them to join us again this winter. When we invited them, the wife made it VERY clear to the husband that he would NOT be diving everyday this time. We've already planned our charters so he'll be able to dive 3 days and still have 3 days to do stuff with his wife.
Food for thought.