In addition to state and national parks good places are BLM campgrounds and those in the national forests. On average the cost we see is $15 a night and seniors with a pass pay half that amount.
Private parks will have full hookups and often Wifi and cable TV. Most of the time the rates are between $30 and $50 a night. The private parks are more likely to have pull through spaces and longer spaces for people towing trailers or another vehicle.
Most private RV parks are conveniently located close to a major highway which also makes them noisier overall than the state and federal campgrounds.
In terms of amenities and showers and overall restroom cleanliness I have found the national and state facilities to be better maintained than the majority of private RV parks.
In some RV parks you are paying for a clubroom and swimming pool and other items that you may not be interested in using and this is reflected in the daily rates.
The best information is online with the state and federal agencies. The guidebooks have been of zero value with the notable exception of the book California Camping by Tom Steinstra which is a fantastic guide for California.
