I took my son backpacking this past weekend with some friends of mine and some of their boys.  It was the first time my son had been backpacking (he's 8) and it's the first time I've been in probably 12-13 years.  It was a great time.  We were up on the Southern slopes of Mt. Hood, on Timothy Lake.  The weather was nice, not too hot.  Far enough from parking lots to cut down on the crowds, but not so far that you felt like you had to struggle to get there and back. There are some images of the spot here.