We did Aulani Spring break 2013 and Cruise on the Fantasy 2014. Ours kids (younger than yours) preferred the cruise. This is weird b/c when you go item by item - they preferred Aulani's kids club, pools, waterslides, activities, beach - flights are close to the same for us from Arizona - but they would choose a cruise over Aulani. When I ask why - Sergio - they just loved our server enough to outweigh all those other factors.
For us adults -it is hard to say - Aulani was SOOO relaxing and so many firsts to experience with our kids - first snorkel, first kayak - we had a great time in the pool and lazy river as a family. We received some rough news the morning of the cruise so I feel we need a do-over on that - couldn't really relax and enjoy it. Obviously that is unique to us.
Check out ages on kids club at Aulani - can't remember if your 11 year old will be in the younger group or older group - but that could make a big difference in how much they enjoy it.