You have to hit up Harbor Walk for lunchtime at HarryT's, I was there last week around 11:30am and the boats were leaving and coming non-stop. We sat on the deck and ate while we watched boats left and right, it kept our little one entertained the whole time!
You also have to try Graffiti's Pizza, great, great local homemade pizza! It's a totally different taste than pizza chains.
The kids would love Big Kahuana's also but I think it's around $40 a person.
Have fun, our family has been going there for 30 years!