Thinking of taking a river cruise that includes Amsterdam and surrounding areas during tulip season. Would we be better off going at another time? Is it too crowded?

Amsterdam is pretty crowded all the time. Wintertime is somewhat less crowded(except around Christmas and New Year). This is a good time to see Amsterdam. Since most of the European tourists visit Amsterdam on weekend trips try to go during the weekdays, which will be less crowded.

If you want to see the blooming tulip fields, you could alseo decide to skip Amsterdam and stay in another city. The Netherlands, especially Holland has dozens of amazing cities and small towns which are far less crowded than Amsterdam, but not less interesting and often more Dutch.

Amsterdam is crowded all the time and increasingly so. For tulips you needn't be in Amsterdam. Instead go to Haarlem or Leiden, but I guess with a river cruise you won't have much choice.