OP,
Once again I encourage you to sit down and talk to a cruise travel agent. Arrangements will fall into place with professional guidance.
There are too many options to choose from and far too mind boggling choices for a first time cruiser to plan a cruise for multiple family members with your price point. You have no idea about cabins, their sizes (small in your price point), deck, location on any given deck (there's a reason forward and some aft cabins may be less expensive than cabins in the middle of a deck), the difference between connecting and adjoining cabins, family cabins....and the list goes on and on.
After your first cruise you should have a feel for taking the bull by the horns and booking on line by yourself. Don't forget this a family cruise and the dynamics will be far different than if you were booking for yourselves.
FYI, even a Crystal heavily discounted cruise is probably beyond your budget. This is also the least kid friendly line mentioned.
While I love to cruise out of San Juan if you are adding air into the overall vacation price you'd best check the air price too.