Just wrote a long post and lost it. GRRR!
Here's the short version.
Glad you had a great trip with your son! I'm planning on riding from Amsterdam to Rome next summer, and will follow the Rhine from near Arnhem most of the way to Constance, but ultimately to Zurich and over the Alps into Italy. Still trying to decide if I want to go through Basel or take a shortcut through the Stuttgart area. I have been to Strasbourg and Baden-Baden, so I know that area is great.
Will be doing a light tour and staying in hotels and probably won't make reservations, except perhaps the day of/before arrival. Not sure what to expect when I show up with a bike? Usually okay to put it in the room, do most hotels have provisions for storage, etc.?
What kind of roads and / or paths did you use along the Rhine? Did you stay very close to the river or just keep it within a few miles away.