Lodging
Days Inn
Carlsbad itself has the usual motor-inn/motel franchises, largely clustered along "National Parks Highway" US 62/180. Days Inn, Super 8, Comfort Inn, another Best Western, and others can be found; none are spectacular, most are acceptable.
Best Western Guadalupe Inn
White City or Whites or White's, just before the park entrance, is largely a noisome tourist trap, but does have the acceptable Best Western Guadalupe Inn formerly "Cavern Inn". The usual Best Western accommodations, with spa, pool, etc. Rooms start at $65 depending on season. Phone 800-215-2167; it's a fairly small property, so don't count on being able to appear unannounced and get a room without a reservation.
backcountry
Backcountry camping requires a free permit and is best in the relatively high country beyond Slaughter Canyon Cave. Pack in lots of water, as there are no reliable water sources in the backcountry for much of the year. When arising in the morning, check your sleeping bag and footwear for scorpions as well as snakes.
camping
There is no car camping within the park itself. A KOA campground is on 62/180 near Carlsbad.