Amsterdam

Do you have Rick Steves' guide book on Amsterdam? If so - good. If not - get it - I found it to have lots of information on side trips that helped us a lot.

"can someone suggest some trips relatively close, although not day trips"?

Huh? Can you describe what you mean?

The Eyewitness Guide for the Netherlands has a very comprehensive lists of attractions near Amsterdam. Just don't use their maps to navigate (pretty to look at, but useless for finding your way.)

Utrecht isn't too far away. It's like Haarlem, but with a rowdy student population. I also enjoyed the Railroad museum here, although it might be of limited interest if you don't know any Dutch.

If you travel in the spring, the world's largest tulip garden, Keukenhof is open.

To the north, there's a large open-air folk museum (De Zuiderzeemuseum) at Enkhuizen.

http://wikitravel.org/en/Amsterdam#Get_out