I guess we have been super lucky. We bring other people almost every time and haven't had any issues really. We took my niece when she was 13 and she loved everything, we took my BF's DD and she was so stoked but she is like one of my kids and when she started to get mouthy a simple, you are going to far, was enough to get her to step back into line like my own kids do, I took another neice when she was 10 and she was cranky like that the first day because she wasn't getting her way (we had traveled for 14 hrs and just went to DTD for dinner and back to the room til to bed and she wanted to go to the park) but after that she was good to go and had a good time. My DD keeps asking to bring friends with us next time but we are going for a long time so we won't be doing it. lol Our trip next month we have my BF and her DD who is now 20 going with us. It's a surprise for my DD 8yrs, and my BF has never been. She is letting her DD and I plan everything because we know and we have promised she will get 3-4 hrs sleep a night lol.