Staying in AMS itself (Mercure)
Yesterday, I arrived in Schipol at 0620 hrs and was only booked to fly out at 2045 hrs. I decided to try the Mercure hotel in the airport itself (opposite the KLM Crowne Lounge at Pier F) and can report that it was a good experience. It is a small room with a bed, TV and desk but when you are only there to sleep it works well. WiFi is included but you have to contact the front desk for the code.
There are several positive factors in my opinion: first, the room is quiet (so nice); second, the room is dark (OK, no windows) and third it s vary convenient. When you eliminate the need to use a shuttle service, you can easily save yourself another 1 hour which translates to another hour of sleep. The only negative is the lack of breakfast.