The Schiphol airport is big, has lots of shops (both duty free and usual ones) and comfortable. I once got stranded 4 hours there and didn't get bored. It's much better to get a train ticket a little bit later than you'd like, and be allowed to fly without worrying. If your plane is late, you'll be OK for the train, and if it arrives on time, just treat yourself to a Dutch breakfast.. or dinner.... or whatever, it's tasty anyways.