Lucky bastards!
Grand Wailea rocks.
Do the Haleakela downhill, on the bicycle, after watching the sun rise over the 'crater'. Go to the bike shop where you don't use helmets; they drive you outside the park and put you on the bike (FULL helmet, like a motorcycle helmet, required inside the park).
It won't be as much of a factor for you living in CA, but if you do the Haleakela downhill the first day (watching the sun rise), getting up at 3A won't be as difficult. I travelled from the East Coast and it was like getting up at 8A. You show up at the bike shop at ~4A and they drive you top the top of the mountain, and you watch an incredible sunrise, above the clouds, overlooking the 'crater'. Then you get back in the van and they drive you right outside the park, and put you on a bike. All downhill to the bike shop, you have all morning to get back if you like. Don't get lost though, like we did, LOL. Dress warmly - it's 30 degrees F at dawn at the top. Sweats and a few sweatshirts should do it.
You can make your reservations online today, or pick up the phone:
http://www.bikemaui.com/alert.html
I think that's the bike shop we used. Good group.
Go to Mike Severns' Diving for SCUBA; very experienced. Did about a dozen tanks with them. Do the night dive in the Molokini atoll - 1 tank before dusk, watch the sun set, then the 2nd tank inside the atoll. I went in Feb and we saw a pod of gray whales cruise by the atoll, within 40 yards of the boat, during the sunset.
Watch the sun set every day; stop the car and get out. Or, nice view from the bar of the Grand Wailea.
If you go to Hana, give it 5 hours+ round trip. Stop often with the camera.
My trip to Maui is certainly on my short list of favorite vacations, ever.
ENJOY!
Edit - PM Brandy for specific questions, she's in Maui!