Maui boring? NO WAY!! Not boring at all IMHO... It's SO beautiful, our family really loves it... We have two children 9 & 6 & they both love going to Maui as well....
Both trips we've taken we've stayed on Kaanapali beach, we've stayed at the Sheraton, the Marriott & the Hyatt... The Hyatt was the most lovely by far, but the beach there isn't so good... you have to go up to the Marriott or Sheraton... Kaanapali Ali'i should be really wonderful.
We took a couple of whale watches, the best by far was in a rubber boat LOL... It was GREAT... I'll look it up & see if I can't get the name of it.... We were so close to the Dolphins, it was TONS better than being on one of the larger boats....
I love Haleakala & no way would you ever find me biking it LOL... The drive up to Haleakala is wonderful, be sure to stop every couple thousand miles & take photo's of the family, if you get lucky, by the time you get to the top, the clouds will be BELOW you in your photo's... It's also great to get photo's of the ocean from that vantage point.....
Luau's? Definitely Old Lahaina seems to get the best reviews (but is the priciest), the one I liked the best was at the Marriott (I know sign me up for the cheese)...
Hana, DEFINITELY it's the journey not the destination. Think about renting a house for a night, we had one set up for about 125.00, that would have been quite the deal, but ultimately we decided to stay elsewhere... Once you get to Hana, continue on past Hana & drive up the West side of the island, that road has been finished off & I hear it's amazing...
If all else fails, sit on Kaanapali watching over to the islands across from it, very peaceful, you'll have a great time!