Southwest Airlines is now working with CAPS (Certified Airline Passenger Service) and offers advanced hotel baggage check in at Mandalay Bay, Imperial Palace, Sahara and Bally's. For a $6 fee, you can go to the CAPS desk 2 to 12 hours before your flight departure, show ID & answer the 2 security questions....your reservations will be confirmed via computer and your luggage will be checked all the way to your final destination (except Dallas Love Field).

DaisyDeuces,
Do you know if CAPS issues a valid Southwest "boarding card" or are their services strictly for baggage?
Southwest boards fliers by their boarding card number. The lower numbers board first, and the earlier you check-in at the gate, the lower the boarding number you receive. If you have a seat preference, you have some incentive to get to the gate as early as possible. For instance, I prefer to sit as far to the front of the plane as possible to minimize deboarding time.