From the "Pre Tour" section of the tour's web page:
"Here are a few suggestions for sightseeing in Haarlem and Amsterdam that we will not do as a group. Haarlem: Frans Hals Museum, canal cruise, Teylers Museum, Corrie Ten Boom House, Grote Kerk (main church). Amsterdam: Amsterdam Museum, Jewish History Museum, Dutch Resistance Museum, Tropical Museum, Heineken brewery tour."
I really liked the Amsterdam Museum, and the Dutch Resistance and Jewish History museums are very worthwhile as well. Canal cruises are great if you're feeling too jetlagged to see a museum (I find that going indoors worsens my jetlag immensely, and staying outdoors in the light helps minimize it). Almost every Dutch city has them.
I was not taken with Delft at all, but many others like it. I really enjoyed Utrecht (covered minimally in Rick's book) and Leiden (not covered in Rick's book). In your situation, I'd get a few guidebook on the Netherlands from the library, read about nearby attractions, and see what appeals. Rick does have good details about transportation from Haarlem to places he does cover, and he has lots of daytrip ideas (the Hague, Edam, open air museums, etc).