You mentioned Taos-- we stayed at Taos Valley RV park. FHU, sites were large enough to fit us and the toad.. length of 65'. Clean well maintained park
Agree. If you boondock you can stay up at the Taos Ski Valley for free--on the parking lot. No hookups, but shops nearby and good WiFi. If your interest is in Santa Fe I would not recommend the Ski Valley as it would add a half hour to your travel to Santa Fe.
You could also check on the Ranchos de Santa Fe campground. It is nearer to the city than the Santa Fe KOA--on the same road. Although we usually stay at Santa Fe Skies we have stayed at Ranchos several times and it is fine.
