The park has a very large welcome area. From the side of the parking lot, there are areas where you can stand and view the countryside for a great distance because the park is pretty high up. The welcome center is very large. It has a large area for helping guests and selling tickets, a nice souvenir shop and a cafe. Once inside the building you should go ahead first thing and get your tour tickets and rent the recorders for the self-guided tour. The ticket and recorder lines get pretty long.
Once you are ready to start your tour, you will take an elevator deep into the earth to the level of the caverns. You can choose as you take the tour how long you want to go because there is a route for a short tour and a continuation route for a long tour. My wife is afraid of heights, so we only toured the Big Room. It had a large variety of formations and they were many colors. At some points, the trail through the cavern came to some fairly high drop-offs, but my wife held to me and was able to get past them. The inside of the cavern has a pretty good artificial lighting system, but it could be better.
We really enjoyed the tour; however, I would recommend a tour of Natural Bridge Caverns north of San Antonio, TX. The cave is not nearly as big as the big one at Carlsbad, but it has some beautiful formations. I thought the color and variety of the Natural Bridge formations were better.