thanks for the tips!

Other things I'm thinking of taking them to do --

Hanauma Bay for a morning swim/snorkel
Diamond Head climb (maybe, don't want to be too tired!)
Drive to North shore with H1 or H3 Pali lookout?
Dinner at Ono Restaurant Honolulu for real local feel and great value.
on Kauai -- Wings over Kauai air tour, which I just discovered (http://www.wingsoverkauai.com/)

Do you all have any comments on luaus? It seems pretty pricey, and the two I looked at (Royal Lahaina luau, Old Lahaina luau) get mediocre or good reviews, but are proportionally cheap or expensive to go with that. I have the feeling you're paying for a lot of people's alcoholic consumption (which is fine if you drink a lot, but we don't). I guess the show makes it worth it?

(edit. ah, found some answers here:
Does it even pay to go to a Luau?)