We are in the expen camp - I find it easier to control the dogs when necessary, and they are more relaxed. We have 4 sets which make a large area for us all to move around in - it is like a small backyard, but unlike many we do NOT allow any peeing or pooping in our "living room".
I like to keep our site tidy, with stuff picked up and put away at all times - our site, with its fence, is usually better looking than many of the sites around us ;-)
I do understand that some parks have had a bad experience and we will tie up if necessary.