The largest hot spring pool in the nation is at Glenwood springs. 

In the middle of the woods there are a few hot spring pools. The location makes it one of Colorado's favorite. After dark clothes are optional. 

There are a few resorts right in town and on the river. 

Sitting below a 14er, this resort has a few pools right on the side of the river. 

Nestled in a little valley , this town has a few hot spring options.