Others disagree, but I think that the airport hotel is awful.
Very colse to the airport, a $15 taxi ride, is the beautiful El San Juan Resort.
If that is too pricy, there are many brand name hotels in the same area that cost less but are of much higher quality than the airport hotel.
If you have a longer layover, you may want to taxi to Old San Juan and stay at the very nice botique hotel, The Gallery.