Our daughter will be attending college in Venlo, we're planing a trip that includes Amsterdam but I'm looking for tips near Venlo (close to Dusseldorf) for day trips without a car.
In nearby Germany you'll be close to Aachen. I had always wanted to see the church so important to the Holy Roman Empire and the bust of Charlemagne. It wouldn't be too far to take a Rhine or Mosel cruise from Koblenz also.
In the Netherlands you can take a lot of day trips by train followed by renting a bicycle to get you further into the countryside and see some canals and windmills up close. Most train stations have bicycles to rent.