I agree - for a one night layover where you don't have a lot of time, the Airport hotel is a good option. In a case where you'll be staying multiple nights or have plenty of time to go offsite, then I would go elsewhere.

Everytime we've stayed that airport, it's been to catch 4-5 hours of sleep. The one time we had a long layover (long enough to visit the Bacardi factory) we stayed offsite at a DoubleTree Hotel (if memory serves me correctly).