There is a park in northern Virginia called Clemyjontri that is designed to be accessible to children of all abilities to play together. Even the adults play as well. I've visited before and after my second knee surgery. It's had around 200,000 visitors a year, making it a very successful park in its own right. People from miles away, even as far away as New York State and Delaware have visited.
There's an interesting side effect to my last visit. It's a rehab facility in a way for me. A seesaw with springs becomes a knee stretcher with someone on the other end. A balance beam with handrails on each other allows me to do a little moving around and stretching my upper leg muscles as well as my being able to move along a narrow path. Another piece of equipment with alternating heights of steps allows me to work on my ability to step up and down on higher/lower steps. A couple other sets allow me to do other exercises.
Sometimes even the right type of playground can become a rehab facility, provided you're there at the right time and kids haven't quite taken over the place.