My husband will be in studying abroad in Cologne, Germany for the month of May. I will fly to meet him and we are planning to explore Paris and Berlin for about 2 weeks. We have to fly out of Dusseldorf, so we are planning on a 1 day stay in Cologne as well to see the Cathedral, etc. Neither of us have ever been to Europe before. We both would like to add one more stop to our trip, possibly in Belgium or Switzerland. Can you give any advice? Is Paris and Berlin enough to see in 2 weeks? I don't want to overdo it.
I did the Paris-Berlin train ride with an overnight stop in Metz. This small Lorraine city has a pleasant cathedral, a nice mixture of French-German cuisine and beer, and a new branch of the Pompidou art museum from Paris. Even its train station is considered an architectural landmark. It was a convenient break in the journey.
When doing your travel math, remember that changing cities knocks at least a half-day out of your schedule, what with packing up, getting to the transport, and finding your next hotel. You already have Cologne, Berlin, Paris and Dusseldorf on your itinerary. Detouring to Belgium or Switzerland will reduce even further your time for seeing the sights, which already is not as long as it seems.