As far as I know the belief is that sleeping in unfamiliar or unusual places/positions/whatever is good for lucid dreaming because it means that you are instinctively going to sleep differently, that you are sleeping lighter because your body is still not accustomed to the environment, and that helps you maintain consciousness or attain lucidity more easily. Then of course you could factor in the placebo effect, or like someone mentioned just the thought that carries on into your dreams of "Wow I'm sleeping on a floor (which I hope you usually don't do)... hmm wait how can I be sleeping on a floor if I am standing on a mountain right now? Oh wait, I must be dreaming!" I know this happens to me a lot when I go to bed way later than I should... normally if this thought is in my mind, like I'm having trouble falling asleep and don't until 3 am, I dream of a clock and realize that I went to bed at 3 and have a DILD.

Anyway that is my belief, and I think why so many induction techniques suggest sleeping in strange places (on your couch, backwards or sideways in your bed or on your bedroom floor, etc.)

I find that when I travel, I'm usually exhausted so I sleep pretty heavily. I'm going on vacation for ten days to my dad's, though, so I'm planning on cultivating some lucids while I'm there. I usually get a couple because my bedroom there creeps me out, so I never get into too deep of a sleep! Add in the strange sounds of his neighborhood and house, and yea... the ideal LDing environment!