The oldest town in the San Luis Valley, Colorado is San Luis. The amazing bronze sculptures of the Stations of the Cross resides here.
Drive further north to Fort Garland to experience the Fort Garland museum and other attractions.
Not far from here is the Great Sand Dunes National Park and Preserve and a family friendly hike-Zapata Falls.
If you are a hot springs connoisseur, like I am, then just drive Highway 17 north going into Colorado. There are four very different hot springs worth checking out.