J.L.
You can ask all your disney cruise related questions to the mom's panel:
http://disneyworldforum.disney.go.com/home.aspx
There is a section for Disney Cruise on there. There is stuff to do all the time on the cruise. Clubs, kareoke (SP?), comedy. If I remember correctly the kid's club is open until midnight. There MIGHT be in room babysitting available but I am not 100%. We went on Disney last October and it was the best experience of our lives. Everything was wonderful.