Higher end comes with higher prices. What $$ per night is going to be too much and you say no thank you? Your question is very subjective because what is nice to me may not be nice to you. I've been to a couple parks where you put your payment through the slot in the door...questionable at first look but turned out to be quite pleasant and enjoyable for us but we were only there for 2 nights.
Hilton Head Harbor RV park is very high end and beautifully kept. Be prepared to put up with nightmare traffic though on the island. I live near Anchor Down in Dandridge TN. High end and a beautiful setting that overlooks Douglas Lake and a view of the mountains. They have stamped concrete pads and stacked stone fireplaces. Very peaceful really.
Down towards you on the Gulf we like Abita springs RV park. It's on the north side of lake Pontchartrain and it's an easy drive into New Orleans and the plantations. Nice area to explore with lots of history and great Cajun food.
Out west we liked the Grand Canyon Railway RV park when we visited the Grand Canyon. Walking distance into town, Williams AZ right on Route 66. It is an hour drive to the GC though. Up in Pendleton Oregon we liked The Wildhorse resort and casino RV park. We had a nice spot though where I noticed some sites were not that desirable, to me at least. Still, I would go back in a minute.
Are you planning on joining anything like Passport America? Coast to Coast? Passport America can pay for itself in 2 nights. The thing you have to watch out for is the individual park restrictions. Still worth it for overnight stays when traveling destination to destination I feel. Coast to Coast requires you to join a membership park that can be quite pricey.
The world is your oyster. We live in a beautiful country and the best way to see it is in an RV. Get going.