Hi, I will be going on my 4th cruise with my kids on April 20
My husband and I have found cruising to be an ideal family vacation with so many nice things aboard, so many nice ports, and the terrific attention the cruise staff pays to the kids. We've travelled on Carnival and Princess with the children, now ages 5 and 3 and have had a wonderful time each time. This time we will be on the Explorer on RCCL.
One thing you might notice travelling with kids, is that you might get through the lines while boarding a LOT faster. We've had cruise staff direct us to special windows to hurry the process so the kids would not get cranky on line, esp when we were travelling w/under 2s. If you have a stroller, you will be escorted to an elevator instead of the usual escalators.
I give you a lot of credit cruising with your grandchildren. I wish my children had grandparents that enjoy them so much that they want to spend even their vacation time with them instead of wanting to do their own thing. One set moved to Fla, and have chosen not to come up and see them since, and the other set thinks babysitting for an hour is a huge imposition.
Vacationing with the children will be like spending time with them anywhere. The children's programs cruiselines have are great, but the children will not be in there 24/7, and the younger ones MAY choose NOT to separate. The good thing is Thanksgiving week is a holiday week and there should be a ton of kids on board for your grandchildren to play with and to make the program seem REALLY appealing. Your vacation will be a combination of enjoying adult and family time. You will get to watch the little ones have the time of their life in the pools and on the beaches, and get to go out as adults too. I think you picked the perfect vacation.