Our 6 month old is sleeping through the night at home and used to sleep fairly well on overnight trips (with us). However, we have just had two weekends away from home when he hardly slept at all. He was in a pack and play (not his usual one - but one we keep at my parents). My wife would nurse him when he cried and he would quiet to feed - but once back in the pack and play he would cry and not suck his thumb as he normally does when falling asleep.
After reading some other advice, next time we plan to bring his usual pack and play as well as his normal sheets (for scent). We are assuming this is just a phase that he will grow out of - but what are other strategies to try to help him feel at home and calm so that he (and we) can get some sleep?