Plenty of good advice. I'll add that the Maui Marriott was nice for our family, kids 10 and 7 at the time. Most of the Kaanapali hotels have several pools/water features for their enjoyment. Have stayed at Kihei as well. Personally enjoyed Kaanapali better, closer to Lahaina. Kihei was nice walking to the little restaurants as well. If you enjoy preparing your own meals, the Marriott (and probably others) have gas grills in some areas. A steak or a burger can be a nice amid all that seafood and sushi.
Black Rock luau was very nice, a bit pricey, but right on the beach @ Black Rock. Nice sidewalk/path connects the Kaanapali hotels to each other.
Have golfed at both Royal Kaanapali and Kapalua. Spend more for Kapalua.
Drive to Hana. Have done it three times, and I still haven't seen everything or done it all out that way. It might be best to drive all the way there (Oheo Gulch and the "Seven Sacred Pools"), then hit all the sidestops on the way back. Usually you get sidetracked on the way there, and then you don't have time to see what you want and have to hurry back or drive that road at night. If you are so inclined, about 10 minutes past the pools at Oheo is a small church graveyard. Charles Lindbergh is buried there.
Have not done the volcano at sunrise (crazy to get up THAT early), but have done it for sunset. Whatever you do, dress warmly. It will likely be in the 50s at the summit and feel like 30-40. We saw people with parkas, hotel robes and, well, others in shorts that froze. Sunset was beautiful.
PIctures, pictures, pictures. Also cannot reiterate the advice about sunscreen: the UV index is usually off the charts.
My daughter (10 at the time), absolutely loved snorkeling. Son not so much. He preferred the pools. Surf is sometimes rough on littler ones. Try to hit sheltered spots. Snorkeling Molokini and Turtle Town were great for her. But you don't necessarily need to spend a lot to do it. You can usually just wade into the ocean and do it.
Have stayed on Oahu, but never at Waikiki. Turtle Bay (north shore) and Disney's Aulani. Aulani is great, but far from Waikiki. If you want action and convenience, stay there. Don't miss Pearl Harbor.
Just enjoy Hawaii. Have a plan to deal with the jet lag, or everyone's body clocks will be off for a few days. I wouldn't try to do a Hawaii vacation in less than 8 days. In 2012, we went for 16. If you can swing it, go for as long as you can.