I would love to do it. I'd go anywhere by train, just for the ride. Going North from Inverness to Thurso is just fantastic. Trains clean and almost empty. I once organised a trip all by rail when I lived in York. 11 of us left York at Night by train to London Kings X, then travelled on the tube to Charing X. Then train to Dover. Boat to Calias. Calais to Paris Nord by train, then metro to Paris austerlitz (?...it was 1979) Then train to Bassle then Lucrene. (Switzerland)Steamer across Lake Lucerne, up the Arth Riggibahn, down the other side by the Arth Goldau, then main line back for Lucerne, then Bassle to Mulhouse (French railway museum) Mulhouse to Paris, metro across Paris to Nord, then train to Dieppe,boat to Folkstone, Folkstone to Waterloo, tube to Kings X, up to York. Great fun.
Once went to Spain and back by train, also South of France.