No really long ones like some of the contributors here, though always enjoyed ferry flights - even those where I got arrested, aircraft impounded, ran out of money etc.
The shortest was an S58ET from Aberdeen to Portugal. I've done many others. Bell 212s UK to Egypt and UK to Teheran, but I love taking helicopters to Africa the best. I've been across the Sahara and down the west coast and I love the west coast routes best. It's always great going through the mountains in Morocco and then either the long sea crossing to the Canaries, or nowadays the route through Western Sahara is also open. It always amazes me seeing where the Sahara meets the Atlantic and sand just becomes sea in an abrupt vertical stop, with the wind whipping the sand from the top. I love then encountering the lushness of the forests and swamps as one arrives in Senegal and the vastness of Mali with that maazing lake with the vertical sided islands in it. The people of Burkina Fasso always make it worth while stopping there, and I'd love to revisit on holiday one day. It's also great if the weather's good, after hundreds of miles of mangrove swamps in the Niger Delta, to suddenly see the bulk of Mont Cameroun on one side and Malabo on the other. I hope I'll have the opportunity to do some more, though as I get older it will probanly be more difficult, b ut I'd dearly love to have the opportunity to finish off the west coast with a ferry from Nigeria to South Africa