Planning another trip to Hawaii

So me and the wife took a trip to Oahu in June 2009 and absolutely Loved it (obviously!). We stayed for 7 nights/ 8 days at Hotel Renew (flying out of LAX) and only had to pay $1500 for 2 roundtrip airline tickets and the 7 nights. We got a weeklong car rental for $200. After meals/activities/gas we were right around $2,200 or so.

I'd like to find a similar deal (with similar price hopefully). We're looking to go there probably in May or June 2011. There's some differences this time though, we have a now 6 month old baby boy who we'd like to take along with us. He's flown before with zero problems, so I'm not too worried about that...he's pretty well behaved. But we were thinking of either going to a different island or do a multi-island cruise. We were even thinking of flying one way, then cruise the islands and cruise home to LAX port (if they can even do that?). If not, maybe fly roundtrip to Oahu, stay a couple days there, then do a local few day island cruise. We want to see Maui and Kauai mainly.

First off, do cruise ships allow kids under 1 year old? Does anyone have any experience doing either of these ideas? Any input would be great, I know we're planning early, but want to get a head start! Hopeing to find a great deal as well! Thanks all.