There is now a bus that take you directly fom the airport to the downtown bus station for less than $3 bucks. I saw quite few hotel nearby but can't remember; check frommers.com

Playa Caribe is right across the street from the bus station. It is also a Best Westren hotel. Playa Caribe is just the name. Nice hotel for a stop over. You can see what it looks like on Cancun.com just click on hotels and then downtown. Yes you can catch the bus from the airport to downtown. You may need to make reservations though for the hotel. The bus terminal is across the stree from the airport where the Charters come in. Should only cost you around 300 pesos to get to downtown Cancun.