If you're up for a cruise, I'd highly recommend something like a Windjammer Boat in the British Virgin Islands, or Nevis/St. Barths, Grenadines, Barbados . . . etc.
Cruise ships offer a lot, but they'll nickle and dime you. And, when you dock, you'll just have ONE MORE opportunity to by those stupid keychains, t-shirts, and touristy things that you don't want.
Small 'tall ships' in the virgin islands can dock in smaller ports, and you can get a much better 'local' experience than a standard cruise ship.
And, I feel that The Virgin Islands kind of bridges that gap between a "really expensive, really safe" Hawaii and a "economical, perhaps a little too adventurous Southeast Asia". Especially with kids.
www.windjammer.com
www.bhtmcruise.com
www.starclippers.com
The prices seem high, but remember; they are ALL INCLUSIVE; four meals a day. Some offer free drink programs, and ALL extracurriculars, like snorkeling, water ski, kayak, boogie boards, surfboards, tubing, is FREE. If your kid wants to boogie board for . . say, 8 minutes, like a kid does, you're not out 10 bucks for that 8 minutes. Wanna go water skiing for 20 minutes, do it. I think it's great.