There are other things to do in AMS.

If visas aren't an issue, you can either take the train into central Amsterdam and walk around or take the tour from the airport.

The airport has a casino (airside in nonschengen), a small art museum, a photo gallery about the history of KLM and AMS, interesting food and drink options, lots of shopping, various seating areas and internet access options, an airside transit hotel for naps and showers, a viewing deck, a land side hotel (Sheraton?) that probably offers day rates, etc.