Canadian in Holland for the last 2 years.
The motorists are very careful around bikes, and generally very polite. Almost all of those drivers are cyclists too.
The routes are many and varied, yet very well marked and mapped.
All cities are ridiculously easy to ride and navigate through.
The islands off the north coast, especially Terschelling are great riding.
Limburg (in the south) is a special treat. All the features mentioned above, but add rolling hills, orchards, and castles.
Come during April/mid May for the intoxicating hyacinths and tulip fields in areas north of Leiden and north of Alkmaar.
Good routes in Belgium also, but don't forget your map! From what I've seen so far, a bit lower intensity of the bike culture there. Especially the urban, everyday stuff.