Morton's Warm Springs, Santa Rosa
This is an old warm springs that was first developed long ago. Its really started to take its current form in abouth the 1940s, with the main building clearly dating from that era.
It has three pools, one a small shallow toddler pool only a few inches deep, along with a large grassy area, several picnic areas under oak trees or along the creek, and an area to explore the creek that the facility overlooks. It has a very picturesque setting among hills on the northern edge of the Sonoma Valley, with thick oak and riparian woodland around it.
This is actually near Glen Ellen and Kenwood, but, while touristy, they are small unincorporated places with little accommodation. It is also just outside Santa Rosa, the nearest incorporated city.
In addition to the directions below, from Santa Rosa one can take Bennett Valley Rd out all the way to Warm Springs Rd and turn left. It will be on the left.