I agree with Erina. We walked everywhere within Amsterdam on our first visit. This past Oct. we also took the trams a few times when it was raining and we needed to get somewhere, but for the most time we walked varying our route each time to see more. We stayed about 500 yards from the Rijksmuseum and would sometimes take a trolley to Centraal Station in the morning, but always walked back and were surprised that it was as close as it was.
We went on day trips from Amsterdam and I agree I think that is the way to do it. Get an early start, distances are short spend the whole day and head back for overnight in Amsterdam. We went to Rotterdam, Harlaam this time.
Regarding Belgium. I agree Brugge is a must, but frankly I was disappointed in Brussels. The museum was wonderful but we were disappointed beyond that. On the other hand we have friends who loved it.
If we were to do it again, I think we'd stay longer in Amsterdam to give ourselves a chance to take more day train trips. Barb