Go to big beach, walk the volcanic rocks at Ahihi Kinau. Good snorkeling there too. Rent scoots and hang out at Kamaole beach 1, 2 or 3 a little north in Kihei.. scooters are a must in Maui for me.
Take the car up to Lahaina and spend a day there. Good shopping and eats. Head further up the road if you want to check out Kanaapali.
Do the road to Hana if you can.. I only made it part way, but great scenery, waterfalls to swim in etc. Google it and see if you're interested.
Oh and do a luau, of course. There is a great outdoor one in Lahaina.. can't remember where.
Eat shave ice with ice cream on the bottom
Edit: Go for drinks at Moose McGillycuddy's and see if my Lions shirt is still hanging in the rafters beside a Rough Riders flag
808 Bistro is a good spot to eat where you can BYOB as well.. I thought that was kinda nice. Both of these spots are a short scoot away in Kihei
