Regarding Yosemite, the valley is a complete zoo in the summer and is best for a day trip. However there are several first come first serve campground in the park that are very nice. Some cater to bigger rigs and some don't. Toulomne Meadows is very nice and half of the sites are first come first served. If you plan to arrive on a Sunday or Monday you can usually get something before noon. As the week progresses you need to be their as early a 6am by Thursday or Friday.
1965 Airstream Caravel
2014 Jeep Cherokee Latitude
V6, Tow Group, Comfort and Convenience Group