I think I may be a little bias as a mom. I am much more relaxed with sons than I would have if I have girls. My sons have gone to sleepovers many time. Yesterday, one of them went for a birthday party at some holiday home and spent the night there as well.
With boys, I do not have to worry that much, I think. Of course, the parents of the birthday girl are there to watch over these teens but as you know, they are capable of doing anything. I am very open with my kids so they do tell me what their other friends probably won’t tell their parents. Personally, I think it is important to be open to them and not be too judgemental and too strict. Otherwise, we wouldn’t know what they are capable of doing behind our back.
Once the trust is there, you can safely allow them to sleepover at some cheap hotel Las Vegas and still know they won’t get themselves into trouble. Otherwise, they may even get into trouble under your own roof.