A First European Tour
The route suggested here is designed for people who are understandably a bit tentative about their stamina and equipment, never having done an extended bicycle tour before. The route is the Danube Cycleway, or Donau Radweg.
The characteristics of the route are; it is well documented, it is designed as a bike route so there is infrastructure, it is mostly off road but on sealed byways, it is well signposted, the country is very attractive and the towns atmospheric, preserved and beautiful, and it is relatively flat.
I believe that the best starting options are the German river routes. Nearly every substantial river in Germany has an associated bicycle route, and there are published guides for most of those routes.
The best guides are part of the Bikeline series published by Esterbauer in a number of languages. The guides provide a detailed description of the route, maps and profiles, as well as some information on points of interest and accommodation. They are excellent. There are also guides by a number of other publishers and some websites with information but few maps.
The Danube route offers several advantages. From the international Frankfurt airport you can catch the Sbahn (light rail) to the Frankfurt Bahnhoff (railway station) and from there get the railway information people to work out how you can get to Donaueschwingen. The major section of this route runs for 1300km from here to Budapest, but you can now continue right to the end at the Black Sea.
Or you can simply ride out from the airport to the nearby town of Klesterbach, where you will join the Main river bike route, which in turn joins the Rhine River bike route, which will take you to Basel, which is not far from Donaueschingwen by train or bike.
To make sense of this get hold of the ADFC EntdeckerKarte, a map which gives you an overview of the major German bike routes. It is an invaluable planning aid.
While it is somewhat disconcerting to simply ride out from a major airport, it is surprisingly easy. The bike path at Frankfurt Airport starts at the door of the arrivals hall.
You will not find useful information at any airport, in my experience, so some planning to get yourself from the airport to the nearest town is desirable. Google maps above shows that if you get to Morfelder Strasse you have solved your problem.
The Danube route is one of the major bike routes in Germany, and therefore in Europe. It is very well supported. As you approach a town there are signs on the path advertising accommodation and other services.
By the time you have ridden a route such as this, you will not need any other help in planning your bicycle touring and you will be well and truly hooked.