McKinney Falls State Park near Austin, TX is a picturesque place in the fall, when fall colors are prevalent, and in the spring, when wildflowers are blooming. The photos in this post are from a fall visit, during a drought, so the water flow over the falls was minimal. After heavy rains there can be a tremendous amount of water flowing in the stream and over the falls. At low flow, one can walk in the stream and over the falls, using care not to slip on the rock, as a fall could result in an injury or worse.
There are numerous camping areas in the park for both RV and tent campers with electric and water hookups.
It can be quite hot here in the summer, so fall and spring are probably the most comfortable times for camping. However, an RV, with A/C and a furnace will be fine for the summer and winter camping.
More information can be obtained at McKinney Falls.