The writer Jan Morris once wrote that food eaten in movement, while travelling, is somehow more satisfying.
I agree wholeheartedly with this, except when it comes to plane food (*shudder*). If a flight is less than 7 hours I will usually not eat on board, unless they provide fruit or some vaguely healthy cracker/sembei. Unfortunately, for long haul flights, my metabolism does require food... if you can call vegetarian plane meals such...eeesh.
However, trains are entirely another matter. I have fond memories of munching through giant onigiri, local cherry tomatoes and mikan juice as I slowly wound my way around Northern Kyushu. I have stopped in Hiroshima for okonomiyaki, and sampled vegetarian oshizushi as I watched Tsuwano's carp-filled canals and tiny orange torii fade into the distance.
When travelling around Japan by train I find the journey equally important as the destination. Watching the fields and mountains give way to beach, or the flat expanse of Aichi slowly turn to Mt.Fuji and then Tokyo. All from the comfy seat of an unhurried train.
But planes... planes are unnatural. Squashed into tiny, knee-bruising seats, without being able to walk about or watch the scenery pass by. The cold, recycled air drying out nostrils and any bit of exposed skin.
Every once in a while it can be cool. On a return flight from Singapore I got to watch a thunderstorm from above, flying over the US I briefly saw the aurora and the view of Mt. Fuji from the air is stunning. But, personally, I find that planes are not well-suited to rambling contemplation, while trains are.