My parents bought a wonderful fifth-wheel trailer last year, and for the second year in a row (it's becoming a tradition!), they invited us for a 2-night camping trip with them.
We went to Muskegon State Park, which we've gone to several times before with our whole family. It's a great spot, because there's a little lake connected to Lake Michigan by a channel, and the campground is right there in-between. So we play on the dunes by the big lake and swim in the little lake, where it's warmer and less wavy.
I say "We swim in the little lake," but this trip i never even considered putting on my bathing suit, because the high temperature was about 73, and most of the time it was in the low 60's.. The kids were undaunted and spent hours and hours, first playing on the dunes, running up and down the dunes, jumping off of them, and digging giant holes big enough to crawl into, and then (with a short break for lunch) swimming, building sand castles, and dumping water over each other's heads. They just played and played and played together, and it was just incredibly pleasant to watch them.
Today was a bit chillier, with less sun, and it was morning, so they only lasted in the water a much shorter time before being cold enough to give up on swimming. So instead we played cards and ate s'mores, and nobody seemed too unhappy about it.
It was a really fun camping trip, even though it was unseasonably cold. We ate hobo pies and s'mores and ice cream. Zane ate his weight in tomatoes from my mom's garden. We watched the sunset. We sat around the campfire. We got filthy and tired. It was great.