short layover time from zurich to amsterdam to seattle ok?

For Schipol Amsterdam, 1.5 hours is enough time. The airport terminal is housed under one enormous building, linked by a single corridor which runs the length of the terminal, so it's easy to navigate through. You will have to pass through an Immigration checkpoint on the way to you gate. There is usually an express line open for those with tight connections; a monitor overhead will show which flights qualify. Security for transatlantic flights is done at the gate instead of a centralized area.

I travel to Budapest often and one of the best routes is through Amsterdam and I always look forward to this great airport. BUT!!! I don't do 1.5 hour layovers if I can help it at all. 2 hours is my dead minimum. Granted you are coming from Switzerland and that's a short flight but if it's at all late or if the airport is busy and you get stuck in security you are going to wish you had more time. You will probably make it. Actually the odds are you will make it but naaaaa, life is too short for that sort of pressure. We just last week did Budapest Frankfurt Houston San Antonio and I had right at 2 hours between the Budapest and Frankfurt flights and we used every minute of the time ... and my arrival was on time. Of course I travel with nothing but carryon luggage and I want to board as early as possible so I can be certain of having a place overhead to put it. The Houston to San Antonio flight was also a 2 hour layover. On this one if we hadn't had GLOBAL ENTRY there is no way we would have made it. We got to the gate 10 minutes before boarding began. I think in December I am going to look for 2.5 hour layovers. What to do if you have too much time? Subscribe to Priority Pass and sit in a nice lounge with free snacks and drinks. We particularly like Amsterdam for the flight over because they have showers so we can clean up and then arrive in Budapest feeling good.

I don't see how one would get stuck at security. In Amsterdam, security is at the boarding gate. The only people in line are those that are going to board the plane. They aren't going to close the gate while people are still in line. If you are late arriving in Amsterdam, alert the flight crew that you have a short connection. They can help you be among the first passengers off the plane and possibly have ground staff waiting to help you - like whisking you through the airport on a trolley. You can also ask ground staff for assistance when you get in the terminal. As Michael said, in A'dam you should be fine - as long as you are booking through one airline. If you are buying separate tickets for each leg, then neither carrier is responsible for delays and that could be costly. If you are ticketed by one airline, then if you miss the connection, they'll take care of getting you on the next available flight, etc. etc.

By the way, if your alternative is to connect through a U.S. city, you will need a long connection time, to collect your luggage and clear customs before checking in for your onward flight.

Another option for you, if you can't find a layover you are comfortable with, is using Condor Air. They have a couple of nonstops a week from Seattle to Frankfurt, so you wouldn't go through Amsterdam at all. I just used them last week and I was very happy. They had, by far, the least expensive non-stops from Seattle to Europe. Zurich to Frankfurt is about 250 miles, so you could fly over or train over, depending on what your itinerary looks like. Condor does not seem to show up on all standard searches yet, so just look at their website if this seems like a reasonable option for you.