Amsterdam is indeed a good place to never cross a strip of pavement (even 3 feet wide) before looking both ways for bike riders - and scooters! The UNESCO site with windmills is pretty wonderful, and well worth seeing. The ruined castle in Heidelberg is quite a site. Let's face it, there's very cool stuff everywhere on that trip.
I was very impressed by Cologne, especially the cathedral at night as we motored downriver - it is illuminated and towered over the old town, looking like a ghost cathedral in the sky. And the good folks there know how to drink Kolsch, nice and cold in 200 ML glasses that are refilled as long as you leave he top of the glass uncovered. Lovely way to have good beer.
I'd post a couple of pix but they're all over 500KB and the site doesn't allow that. I've tried changing the image size but the file size doesn't change. I can't figure out how to reduce the file size so they will upload.