I used to take the train to Paris, Gare de L'Est. As the train used to leave early in the morning the great luxury of the trip was the petite déjeuner in the dining car. Somehow, it just tasted better when being able to watch the country-side passe by or meet interesting people.

The longest train trip was from Basel to Copenhagen - but amazingly it did not stick as strongly in my memory as the Paris trips.

School excursions also used to be by train. I can't remember all of them.