Long distance rail travel

I'm thinking of taking to train across Europe, for a sailing holiday on the Med. I know that most would fly, but I'm retired and have plenty of time.

I know it is possible to go all the way to Greece, but that involves Balkan railways, or else to Gibraltar, for instance. I'll be grateful for others' tales of long-distance rail travel, if only to know that it can be done and be enjoyable rather than a traumatic experience!

John