Here in Texas, we have an outstanding State Park system. But like you, I'm at that point in life where one (on occasion two!) 3-day weekends each month throughout the year and then the week of Spring Break are our limits. Still need the jobs to pay the bills and keep funding the retirement account!
From my experience, state parks have been less expensive and provided more space. The private parks I've been to have looked nicer, but carried a higher price and I've been much closer to my neighbors.
If I could retire tomorrow and spend more time in the trailer? State parks would still be my number one choice, can't beat the space, trails, outdoors ... and price.
Good luck, keep us posted on your travels.
Tom