White Sands is a marvel, an extremely underrated park, oops "National Monument", that should and probably would be inscribed instantly if not for the use of the US Army missile testing in the area!!
Start out with the usual visitor center. The video introduction to the park is wonderful to prepare you, the slides at the exhibit a little basic, the gypsum sandbox to fake footprints is cute. The gift shop is actually bigger than the visitor center. The park (covered by the annual interagency card) is a further few miles in. I hiked the first few short trails but it didn't seem so impressive, also I got totally distracted by some dude letting his dog off the leash and trampling the bushes. The "back" side of the park is the real gem. Leave the crowds and sand plows behind to see blindingly white dunes. Take the grueling 3h Alkali Flats Trail over these dunes and through untouched (since their last shift) areas, spotting animals (only saw a mouse and lots of white earless lizards) and taking plenty of pics. The dunes keep shifting so each hike is slightly different. Pro tip right now: do this really early morning! You can also do a sunset walk with a ranger but I didn't feel like hanging around the park all day for 7pm. This is not the same 3h hike btw.
White earless lizards are one of the aspects the park has for inscription: adapt to survive, don't blend in or you are eradicated. Only pale animals are surviving here (generally). The video also showed monsoon season which is technically when you would spot more animals with ease. Unlike deserts around the world, the gypsum is hard and the little water that drops from the sky keeps at the surface creating a short period of ponds and lakes.
Unfortunately most people only come here for dune sledding, probably 75% of the crowd, and then there are those dog walkers (seriously, poo on the dunes?!)
Many animals can be found here including bobcats but none of the big ones will appear during the day. It's just too hot.
I'm hoping the missile tests are moved and maybe by the 100th anniversary in 2033 it could get inscribed, but I'm not holding my breath. Consider this a de facto WHS and add it to your travel plans.
Pro tip: the park opens quite early, 7am in summer, but the visitor center not until 9am. It's advisable to do the Alkali trail as early as possible because it gets brutal hot, and don't ignore their advice of taking water, a compass (!), obviously your phone but also the hat/sunglasses combo. I wouldn't recommend doing this hike at dusk.