Passes do you little good if you need a single round-trip ticket. Passes usually cover just a daytime seat. But travel is unlimited during the pass dates. Some passes specify unlimited travel on certain days of the week, giving you sightseeing time in between. As with Amtrak, foreign trains offer promotions that include companion passes for two and group passes for three or more.
Some passes have only full-time options.
You can travel on any day on which the pass is valid. Other passes are flexible, good for travel on a set number of days anytime during the pass' validity period. The key is to buy the narrowest pass that will get you where you want to go. For multinational travel within Europe, the Eurail pass is best. It includes 17 countries in Western Europe and, Hungary and entitles you to free or discounted travel on some suburban trains, private railways, national buses and even some ferries and excursion boats.