I love Freedom of the Seas for families. If there are 6 of you, you'll need two rooms. If you book early enough, you travel agent should be able to find two connecting rooms for you, whether you're looking for a room with windows or without.
If your kids are old enough to be semi-on-their-own, you may even want rooms across the hall from each other, with you having a room with a window and the kids having a less expensive room, without a window. Or you could keep some of the kids with you in your room and let the older ones have the separate room.
In any case, Freedom of the Seas is a huge, wonderful ship with lots and lots of great features and things to do for adults and kids. However, it's usually a bit more expensive than some of Royal Caribbean's other ships, since Freedom is the latest and the greatest. I'd talk to an experienced cruise-selling travel agent to flesh out your options, price points, etc.