vacationing with them, even when they were that age. I love looking back at the pictures and talking about those trips/vacations with them. We usually go on several 2 or 3 night camping trips each year, and one longer one. Last year we did one that included stops at Yellowstone, Grand Tetons, family reunion, etc. 17 nights total all in a tent. We've also done Disneyland and other non-camping trips.
To me, it's all about keeping he kids well rested and not trying to do too much. We usually plan one "rest" day where we don't do as many planned activities for every one or two busy days. If we're camping our rest day would be spending more time at camp, cooking good food in the dutch ovens, etc. Busy days would be hiking and other more strenuous activities. On a several day trip to Disneyland we'll take a day in the middle and just rest and go to the beach.
I've never yet gone on a vacation without kids though. So my opinion could change in a couple weeks when we do that for the first time.