We have stayed at Wawona a few times. We only stay there if we have not reserved a site in advance. You can visit the camp office and see if they have any openings the day of your arrival. It is close to the road so there is some noise from it. The river runs close to the campground. It is about one hour from Yosemite Valley.
This is our favorite campground at Sequoia National Park! You can get spots by the river if you are lucky. We have even been lucky to get a spot there without reserving a site in advance. We have been happy with all of the sites we have reserved. We would recommend it to anyone!
We enjoyed staying at Mt. Ashland. It is a marked campground that is FREE. Simply follow the road past the ski area and you will find it. All of the spots with fire rings were full when we got there, but there was space to park in the turnoffs or off-road past the campground for more private camping spots. It was quiet and peaceful. We stayed one night and we would stay there again! Great view from the mountain.