There are so many options for day trips available within Amsterdam. Please let me know your favorites! I'm considering the tulip fields, Kinderdijk (for the windmills), Delft, Gouda, or Alkmaar. With never being to any of these, I'd like to hear from others' experiences.

Here are a couple of threads for some ideas:
http://www.fodors.com/community/euro...sterdam-13.cfm

http://www.fodors.com/community/euro...here-to-go.cfm

http://www.fodors.com/community/euro...msterdam-7.cfm

What month are you going to be in the Netherlands? That will help determine whether or not you'll see any tulips.

For windmills, Zaanse Schans is a closer option than Kinderdijk.

Thanks for the thread links. We'll be in the Netherlands around the end of April. Which is more scenic: Kinderdijk or Zaanse Schans?

Kinderdijk is much more scenic than Zaanse Schans, many more windmills.

Hetismij is right;
Kinderdijk IS much more scenic than Zaanse Schans, but I still might go to Zaanse Schans`over Kinderdijk. Walking among the windmills is quite atmospheric, but there's nothing else really to do at Kinderdijk other than to look at the windmills. Kitschy though it may be, Zaanse Schans offers a little bit more to see while still offering you the chance to see a few windmills.

yop

You could do a boat trip from Rotterdam to Kinderdijk, and combine it with the city of Rotterdam, or combine it with visiting Dordrecht or Gouda or even Utrecht.
Zaanse Schans maybe has more to do in situ but it is very touristy. Last time I went it was overrun with Chinese tourists.
You can book a tour to Zaanse Schans from Amsterdam or do it yourself by bus.

For the end of April, do Queen's Day in Amsterdam, 30 April. Also Keukenhof on a sunny day.