I agree the swim with the dolphins in Freeport is a great excursion, but the youngest won't be able to. He must be 12 AND 55" tall.
However, if all of you like seafood, go to Arawak Cay in Nassau for lunch. It is where the locals go and very good. If you take a Jitney or taxi and tell them you want local food, I am sure that is where they will suggest.
Happy Cruising,
Lena