Yes it's worth a stop. A half day up at the Great Sand Dunes National Park is almost a must. There are several hot springs along the way in the San Luis Valley. One in town of Salida nice but kinda like a pool, also Mt Princeton Hot Springs or Cottonwood. Also south of Alamosa is the Cumbres Toltec railway (https://cumbrestoltec.com/schedule/)a bit pricey but really neat if you don't do the Durango-Silverton railway. I think it will be too early for fall colors. It's a long drive and there is so much to see. Enjoy!!! Check out Roadtrippers app.