The high speed train to Amsterdam was very smooth and we enjoyed a canal cruise and our group dinner that evening. A few of us walked around the "Red Light" district - we're in our early 60's and found it very eye-opening! Don't take young children or teens there.
Don't miss the Ann Frank House tour - extremely moving and interesting. Took a bus tour of Amsterdam prior to being taken to the ship, where we waiting for 4 hours to board.
Our last port, Copenhagen, was interesting. We toured the Rosenburg Castle and saw the crown jewels. Tivoli Gardens was okay but if you've seen it once, go somewhere else. We only had about an hour there so didn't have time for lunch in a sit down restaurant.