I can well understand why you would want to leave the airport - any airport, Schipol included - these are some of the most boring places on the planet to be stuck at. Unless eating, drinking, gambling or shopping (most often actually at above loval high street prices) are something you regard as attractions then an airport is not somewhere you want to be. Unfortunately you will not see much in the short time available to you. There are two options worth looking at. The first is to ask the information staff how to get to the nearest park, just to get into more attractive surroundings between flights. The other may no longer be there (after being a regular KLM user I dumped them following particularly bad treatment and subsequent official lies in denial of the facts of it). There used to be a gallery in the airport with Rembrandt etc. on exhibit - sadly, I never had long enough between flights to go in but had promised myself to do so someday.........