I guess if baby's family members were right beside him then there's not much else you can do. That said, if they were not where he could immediately see and even touch them, it's not something that I would personally do while on vacation. The strange place may already be making him uncomfortable and even fearful, and not responding to the need for comfort could be a bad thing there. For me, I would never make my daughter cry it out except when a) I know there's nothing wrong, b) it's well past bed time and she's just refusing to go to sleep, and c) she is VERY familiar with the surroundings. She has three different crib quilts, and at any given time one of them is with her, along with her stuffed bunny (this last obviously only works for older babies). When we moved her from her bassinet to the crib, and again when we moved her to her own room from our own, the move went almost seamlessly because she still had these very familiar things with her. She also did very well spending the night with my mom, because we sent the same bed things she was always used to. I think the key here is that she learned in a very comfortable environment first, and then is allowed to take pieces of her comfortable environment when she goes elsewhere. Every parent does things differently, but I personally would do everything I could to comfort my baby if she was in a place she'd never seen before and didn't have her familiar bed stuff.