Hi Maver,
All the above is true.
To sum it up:
(a) Mainland Europe is a great place to go touring.
(b) Many of the best roads lie off the motorways, just as they do in the UK. That being said, motorways have their uses. They get you quickly from A to B and can cut out some major towns and cities. The French, being sensible, often make their toll motorways free, if used only as a by-pass for a few junctions.
(c) Whilst not all French motorways are toll, it's a reasonably safe assumption that many of them are. Similarly, it's a pretty good rule of thumb that Continental motorways have the E prefix, alongside the 'normal' host country's designation. For instance, in France the big motorway to the south is the A26 / E17.
(d) Whilst not cheap, the motorways are not prohibitively expensive for a motorbike. Again, you get what you pay for. The road surfaces are pretty good and the service stations / food halls / pull-off areas are often of a tidy standard.
(e) The ViaMichelin and / or even a pretty basic GPS will give you routing directions, missing out motorways and / or toll roads. Some will give you the total cost of the journey, including separate fuel and toll calculations. However, in my view at least, nothing beats looking at a couple of good maps to plot a day's (or weeks' of) riding.
Here's a link to the ViaMichelin website:
http://www.viamichelin.com/viamichelin/int/tpl/hme/MaHomePage.htm
and a link to my advice on maps for France:
http://www.ukgser.com/forums/showthread.php?t=104516
(f) Lots of good roads in France and Belgium. Holland, I am ambivalent about. Flat, boring, worryingly tidy, inventors of the speed camera and lovers of caravans. All a bit too much for me.
(g) One last tip. France is a big place, roughly twice the size of the UK. It's easy, with our maps, to think it is about the same scale as the UK. Places are often further apart than they might seem.
Get a feel for the distances and compare them with similar mileages in the UK. For instance, Norwich to Newcastle (via motorway) is 300 miles. Norwich to Penzance is 440 miles and Norwich to Inverness is 630 miles, all via motorway. If you would baulk at doing runs this long in a day, in the UK, it becomes no easier / quicker over the Channel. If you come off the motorways, riding down the nicer N and D roads (like our A and B roads) your average speed will fall, quite dramatically. Lob in fuel stops, pee breaks, fag attacks, getting lost (a big part of the fun) and the day will vanish.
(h) Have a great time.