civicmon: The "Marriott" you referenced at MEX, I believe now goes under this name..

Camino Real Aeropuerto Mexico
Mexico City, Mexico (MEX-Juarez Intl.)
located in front of the domestic terminal B of the Benito Juárez International Airport, just steps away from the Circuito Interior expressway northwest bound side. The hotel is literally right across from the domestic ticket counters, and then a short 2 minute walk across a footbridge to the main lobby.

It is a presentable hotel, but the rooms/food are sub-par once you're inside. If you have a late arrival or early departure, I do think this place is reccomended as the "on-site" hotel at MEX.