I'd recommend Michelin maps, they're comprehensive and also show "picturesque" routes. I'd back Hem up on his comments about route markers, I followed the Nordsee Kuste route a couple of years ago and kept losing it so the map is an essential.
If you're planning on buying a bike over there, you'll have plenty of choice. The standard "Dutch Bike" will do very well as the equipment includes a rear rack, mudguards (sorry, fenders) and a horse shoe lock. Cycle paths are everywhere.