If I have 6-8 hours to kill at Schipol, I thought of taking a train or express bus into the city for 2-3 hours. My luggage will have been checked through to the States already. Dumb idea?
This is a decision you can make on the day when you see how much time you have. 8 hours I would probably do it. 6 hours, might be too close for my risk-averse self, lol.
Have you been to Amsterdam before?
Yes, I will have spent several days in Amsterdam prior to this final stopover before returning to the US. I will have a thing or two I want to see (or see again) if I can take this quick trip into the city. There's an express bus and a train; looks like the train goes to Centraal Station, and the bus closer to the museum district. Have you taken either from Schipol?
How much time do you actually have? 6 or 8 hours? Also where will you be arriving from and where will you be going to? In other words; will you need to go thru passport control upon arrival and/or departure?
Whether or not you’ll have the time to get into the city depends on the answers to these questions.
There is a Yotel at that airport. I’ve used it once for a long layover between two long flights. A shower, a nap, it was very refreshing.
Besides the previous questions about actual time on the ground and the need to go back through security, I'll also ask if you'll be toting a carry on bag? Depending on what you want to do, you may not be able to take a bigger bag inside (e.g. museums). There are luggage storage lockers at the airport but that will deduct some time from your time killing window.
Re: figuring out your actual time available to do things, you can use the Schiphol day planner to see how busy the airport will be on your actual travel days. It populates about 2.5 weeks ahead of time. If the airport is listed as "busy" you'll want to give yourself ample time to get back through security. Make sure to add on extra time you'll need due to extra gate security for your onward flight to the USA: https://www.schiphol.nl/en/my-travel-day/today/departures/
No matter where the OP is flying to, they will always need to go thru security. But that’s not really the issue here, since you can book a time slot for that and be thru in about 5 to 10 minutes. You can book a time slot for the security check on the airport’s website
https://www.schiphol.nl/en/timeslots/?lng=en
The issue is whether or not the OP will have to go thru passport control on the way in and/or out of the airport. If the OP arrives from a destination outside the Schengen Zone they will have to go thru passport control in order to leave the airport. This can take considerable time, depending on what time of day your flight arrives.
If the OP flies out to a Non-Schengen destination they will have to go through passport control again, which again can take quite some time.