I've just today received my Rhein Radweg books 1 and 2 (I already had 3) which covers the area you are thinking about.
You could basically follow the Rhine from Basel to Rotterdam. It's scenic but not particularly fast as the cycle routes are very touristy.
I've done part 3 of the Rhein (from Mainz northwards) although I didn't go into Holland on it.
the books that I recommend are here:
http://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=bikeline+rhein+radweg&x=0&y=0 They are in German but that doesn't matter too much as they have lots of maps and information on hotels that are bike-friendly, although if you can read German they are extra helpful as they tell you a bit about places through which you are passing.
I shall be doing Bodensee/Basel to Düsseldorf next May/June so will be doing most of the Rhein.