Nice to read this thread as we're considering doing this soon. Does anyone have experience in the last year or so? I've heard it's possible they do not allow Chinese cars into Thailand anymore. Could this be accurate? If that is the case, has anybody who's taken this route have an opinion if there would be a safe place to park a car and then take a bus for the Thailand portion?
Maybe you're on your trip already. I don't know about other places, but there are night buses between Kunming and Shangri-la. I was just through Pudacuo again last weekend. Much quieter, but on a sunny day still quite pleasant.