My kids are still on the younger side (14, 11, 8) but we find that avoiding too much downtime keeps our vacations as bicker-free as possible. We stay active, exploring new cities or finding local activities. One or two beach days would be our limit for sure. Everyone bonds and gets along better away from "life". We have a boat and take kids' friends out on the lake all summer long. But our family vacations are sacred to us as a family and I don't foresee many involving friends in the near future.
Mom to Two Wild and Crazy Boys and One Sweet Baby Girl