I've never stayed in a RV park that I thought...this is perfect. I find something wrong with all of them, but I've never paid more than about $60. The Disney RV park in Florida is supposed to be nice but I have no desire to go there.
I haven't seen too many upscale joints in the places we travel. Maybe tourist traps like Gatlinburg.
I believe there are RV parks that only accept Class A motorhomes. You may want to do a search for more advice in the Class A forum here, or look in a forum for your brand of MH.
I'm guessing they are not on every corner though, so you may have to overnight in a normal park in between stays in a upscale park.
Maybe there's a secret list somewhere I haven't seen.