We have a 5y and 18 m/o, and travel fairly regularly. 5 y/o has been fine in a bed without a rail since 3, although he was in a crib until then at home - never once tried to climb out. Prior to 3 and with our LO, we do a mix of things in hotel rooms. We usually request a PnP and set it up. If kiddo will sleep in it, awesome, and it usually at least helps with a safe place for naps. If kiddo won't sleep in it at all we break it down and make a "nest" with bedding on the floor. Throw down a couple of blankets and a pillow, and a parent can lay there with babe until s/he falls asleep. No risk of rolling out. If we're driving on vacation we bring a child-size bedroll that MIL made that can be used for this purpose as well. Finally, if none of the above work, DH and I split up and each sleep with one kid. I get the smaller one, because mommy instinct means I sleep with my arm curled around him so he won't go anywhere. Have fun on your trip!