I too was going to suggest a cruise. The nice thing is the kids can roam around the ship freely, And you can choose low-key activities on port days. I wouldn’t do any majorly busy itineraries if you want to relax. Maybe choose one that has more sea days. I find we get a lot of family time on cruises because the evenings are forced relaxation and we tend to hang out in the buffet and play board games or what not, In addition to the occasional show or trivia contest etc.. Whereas on land we are tempted to sightsee and roam around until late.
"Friendship is born at that moment when one person says to another, "What? You, too? I thought I was the only one." C.S. Lewis