The Darjeeling Limited

I asked our travel agent to cut the flight from Bangkok to Chiang Mai and instead travel by train in a sleeper car over night. It's a 9-10 hour train trip ...

"The scenery on the last third of the trip up into the mountains approaching Chiang Mai is particularly good, you can awake to the pretty mountain scenery as the train enters the highlands and traverses Doi Kuntan National Park and mountains between Lampang and Lamphun. And even on the sleeper, watching the sun rise from the train in the morning is a great experience. From Chiang Mai Railway Station you can take a tuk tuk or songtaew (red truck) into the centre of town."

And, it does, have air conditioning.