We're in the same situation. We did 3 nights on the Dream a few years back. Just did 5 nights on the Wish. I'm ready for 7 nights now. Five didn't feel long enough at all although it was nice to at least have a sea day to check out more of the ship. With 7 nights, I like that there are more sea days as well as port days. Of course I haven't experienced it yet (booked a placeholder but haven't converted it to a cruise yet) but it seems like there will be less pressure to cram it all into those few days like on a shorter cruise. And I would think with your larger party, that's a good length of time. Time for lots of things together and time for people to split off and do their own thing like spa time, Palo, etc.