We did Amsterdam on our own, and it was great. Our ship docked about a 20 minute walk from all the major sights, and the ship ran a shuttle. We used the walking tours on www.frommers.com
and did the canal boat tour from the main train station, near the location where the ship docked. We also took a taxi to the Anne Frank house, and I hope you do not miss that, and the Van Gogh museum. It was a lot to see in one day, but I'm glad that we did because it was a great day, and we didn't have to choose. I hope you have a great time.