Located in Alamogordo, New Mexico, this National Park preserves the white gypsum sand dunes. The park doesn't take a long time to go through and there are a few boardwalks with interpretive signs along the way regarding wildlife. However, a majority of the Park is walking on the sand itself. Not sure I'd go hours out of the way to see the park but if you're on the way by, check it out for sure.
Pro Tip: If you want to sled, bring one and have wax. Otherwise, pay park retail prices for whatever equipment is available at the visitor center.
Pro Tip: You can sled down the dunes. Bring a cheap sled AND some wax to the Park with you or buy them at the visitor center. The wax is key. I had a new sled but it wasn't fun or fast.