A bit farther north with fairly warm winters is Hot Springs Arkansas. Catherine's Landing RV Resort with access to Lake Catherine. Back in site $545.99 per month includes electricity. Lots to do in the area.
Farther south in Freeport Florida is Live Oak Landing. $674.99 per month includes electricity. 11 miles to the beach. Quiet park, beautiful shade trees.
Note: many parks add electric charges to their monthly rate so be sure to compare apple to apples.
If you don't care about being near the beach, we also like Williston Crossings in Williston FL. $627 per month plus electric.