This week we went camping at Spring Canyon by Grand Coulee (see Google map here).
We spent two entire days at the sandy beach--it was hot, even in the shade--where I sat and didn't do a damn thing. We also went on a canoe trip on Crescent Lake, which, though it is beautiful, is an old sewer. (On the map, Crescent Lake is the little "C" shaped lake just south of the dam.)
The night before we left, we saw the laser light show at the dam, and yesterday, we toured the visitor center for over an hour. We had a great time.