hi there
when we go to visit my parents or dd stays overnight at MILs, I always make sure she has the little things she is familiar with. For example, she has 3 CDs in her room that we choose from to listen to while I wash & dress her in the morning, I always take those with me. I always do her bedtime routine exactly the same way, so she plays in her cot with a few toys (I take those with me so she is familiar) and listens to her CDs while I prepare her bath, then we have the bath and I take her favourite 2 bath toys along, then I dress her and we have her bottle whilst listening to her lullabies. It's never failed yet- she has always slept just as well as at home!
hope you have a good trip xxx