TL; DR | Carlsbad Caverns is enormous and very much worth the visit, despite being located next to a whole lot of nothing.
We didn't spend a lot of time in Santa Fe, mostly because we had a six-hour drive there from Sedona (we also didn't have a whole lot we wanted to do in Santa Fe, except go to Meow Wolf for the George R.R. Martin exhibit, which was closed by the time we arrived. Oh well). What we did do there was get some excellent take-out from Jambo Cafe (African-Jamaican fusion) and binge-watch The Amazing Race (we feel like we can relate to travelers who move from place-to-place). As unexciting as this sounds, it was really nice to relax in an actual hotel room and do nothing. The next morning we spent several leisurely hours at a local cafe working, then hit the road to our Carlsbad KOA.
As KOAs go, this one was weird (and we say that having passed through Roswell, NM, which had less alien stuff than we thought it would). Our “campsite” was located in this odd corral-type structure with a serious bat infestation. We arrived late so no one was around (and the campground was pretty empty in general). There was a strange smell and a whole lot of bunnies, and that is about all we can say about this camping spot.
The next morning we drove to the reason we had selected a route requiring a KOA; the Carlsbad Caverns. This park is very cool; the caverns are enormous, requiring a little over four miles of walking on rock made wet from the high humidity (90%+ at all times) to see the whole thing. The place opened to visitors in the 1920s, well before most of the common park preservation practices (woo alliteration!) were established, so there's a big restaurant and gift shop with fully furnished bathrooms buried within the caverns. They even have a suite of elevators which normally take guests down to the grand chamber (and back up again) but it was out of order when we went, so we watched a lot of fellow tourists walk down a few hundred feet and then turn back anxiously. The climb all the way up and down is steep, but stunning; the number of different rock formations as well as sheer breadth of the cavern is impressive, and we felt lucky to be able to take it all in.
As we had a flight booked out of Austin for Friday, September 16th, we were operating on a clock to make it across western Texas. We spent one night in Pecos, a very small town that seemed primarily built for people working on oil rigs. There was not a whole lot to do there except eat mediocre Mexican food, which we did before heading east to Austin.