When I went to Maui, we were in Wailea, looks like you will be just up the beach from there. The entire island isn't that large. Can drive most everywhere in a couple of hours, tops.
We were, very fortunately, hosted by the company my wife worked for, at the time, so we stayed at the resort most of the time. The one thing we did do was drive the Hana Highway. It was pretty spectacular! Lots of pulloffs along the way to look at waterfalls and scenery. If you do happen to take this adventure, stopping at Coconut Glen's side of the road ice cream stand is a must! He's fairly close to the Hana end of the trail. We drove ourselves but it might be worth getting in on a van tour, as they will have a guide that will point out interesting spots, and you will be able to look. I missed quite a bit since it is a relatively treacherous drive, only 52 miles, but 620 curves, 59 bridges, of which 46 are one lane, and sometimes sheer drops to the north side of the highway. We atelunch at a small joint in Hana, and then we stopped and swam at the Waianapanapa black sand beach, which was fun. Stopped at Glen's on the way back for a sweet treat.
Maui is beautiful. I'm excited for you to go! I'm sure you'll have a great time, no matter what you end up doing!
--Jeff