My wife and I will be in Amsterdam at the beginning of October. We would like to do a day train trip to Germany. any suggestions of where would be a good and doable trip?
Duisburg, Köln, Dusseldorf are within easy reach by high-speed trains (ICE), without making it a trip long enough to not leave you much time to enjoy the place.
How much of a radius from Amsterdam are you willing to go? Two, close to three hours? Take the early train, you can get to Kleve, a nice small town, aside from the above suggestions.
We drove from Amsterdam to Koln (but not back). IMO it's too far for a daytrip by car, but high speed train may be workable. Once there, everything is walkable. The train station is right next to the Koln Dom, and Roman museum, the Rathaus is a short walk, and there are plenty of places to eat in the area.
The same fast ICE serves Duisburg, Dusseldorf, and Köln, in that order, with Köln taking 2h40m each way. Prices to Köln range from 29 to 65 euros each way in 2nd class, depending on how soon you lock in dates and times through DB, but there's no deadline to buy them. Note that Amsterdam Central station takes cash, not US magnetic-strip credit cards.
Thanks to everyone for your input. I am going to have to now research each town and see what one would be the biggest bang for our buck.