Given those perameters I would suggest:
Pioneer Town
Rimrock
And
Whitewater.
Totally forgot Whitewater!
It's an interesting area with a river, wading area, catfish ponds, and camping! Ooooohhh and lots of hiking trails!
The nature conservancy has a trail from White Water to Desert Hot Springs.
There is even a trail that you can hike to Canada from. I think it's the Pacific .. something trail.. sorry, can't recall the name. My kids and I spent many days cooling off in that river!
The Wildlands Conservancy's Whitewater Preserve is 2,851 acres surrounded by the San Gorgonio Wilderness and includes the year-round Whitewater River. The Preserve is open daily, free of charge, for hiking and camping, and provides access to the PCT and Sand to Snow National Monument.
wildlandsconservancy.org
Located in a transition zone between the Sonoran and Mojave deserts lies The Wildlands Conservancy's 4,760-acre Mission Creek Preserve. Visitors are surprised to discover the center of the Preserve is a lush wetland with a backdrop of eroded painted hills and Mount San Gorgonio. The Preserve is open
wildlandsconservancy.org