Did she have her own room both times or?
We recently went away and we stayed 1 night in Taupo, next night in Auckland and night after that in Taupo again and the first 2 nights she was in with her Grandma and she would not sleep but the third night we put her in the lounge part of our motel room and she slept fine (wonder if it is because she normally sleeps alone at home in her room??) anyway it could also have been that she was used to the portacot too!
We also stayed the night at MILs the other week and she wouldn't go in the portacot but happily slept in her pram (slept through the night for the first time too!

)
Anyway no real tips other than try keep her bed routine the same if you have one... EG for us we also start with a bath at 6 and get her down by 6.45-7pm for the night. We couldn't have the mobile but she's used to going to bed without it (when batteries run out).
If she has any fave things that help her go to sleep, blanket, dummy, nightlight... Teddy maybe then bring those.
We're going away at the end of the month to Chch, Dunedin, Picton and Hamner (sp?) for a week, spending a couple of nights at each place visiting family and the plan is to just keep everything the same as best as we can! FX!