As an afterthought, I took my GPS loaded with City Navigator, Europe on a three month tour of Europe. Even though we did not use it as described in most of the posts, I'm glad we had it. We started in Lisbon with the only thing planned was the first day's route getting out of the city, and a list of countries and cities we wanted to visit. The plan for getting out of the city changed before we got out when we talked to the ticket agent at the ferry terminal; he knew a better route. We managed 7 countries relying primarily on Michelin Maps, with some backup from the GPS. We find the maps better for looking at the big picture with good road detail, and would usually plan our route for 2-3 days in advance. My wife and I are a firm believer in serendipity, and sometimes our route changed daily depending on campgrounds, towns, attractions, interaction with other riders or locals, etc. The GPS worked well for finding alternate routes when we were on established bike routes such as the Rhine Route or Eurovelo Route 6.
Except for large cities, there was not a need to have the unit visible at all times, nor was there a reason to have turn by turn directions. It was usually stowed in my jersey, bar bag or in my rain jacket pocket. It was a real time saver navigating through large cities. It was also great for finding campgrounds, hotels and other points of interest.
Copy of a slide from one of our Power Point presentations