**I read your Edit: it does NOT matter, how old your kids are. They are 6 & 7... these are young kids.
Kids this age, do NOT have, the cognizance to self-regulate themselves.
When I traveled with my Husband and daughter... I STAYED in the hotel room as my daughter slept. My Husband meanwhile, went with his friend to go gambling. This was in Las Vegas. NO way, would I have left my daughter in the hotel room, as she slept. So what if I was bored or only read a magazine or watched TV. I stayed with my daughter as she slept.
If you and Hubby wanna go out until the wee hours, because you are on 'vacation'... then leave the kids home, with Grandparents, and do not take them with you. Thus, it will be an "adult" vacation... not a "family" vacation.
A baby-Monitor, is not a parent.
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Okay, is your DH the only one and the only adult and the only Parent, in the room with your kids??? That is what it sounds like, from your post.
Are you going to be there????
If not, then no. I would not, use a baby monitor and then him going to the next room(s) after they go to bed.
NO WAY.
Of course not.
Do you know, that there has been a case or 2, of kids being left in a hotel room, while the parent(s) then went someplace else in the hotel, and the kids were then missing? I think in one case, they have never found their kids. Probably abducted or already dead.
Here is the link about the article about one of these cases:
http://www.abc.net.au/news/stories/2011/05/13/3216762.htm
Again, these kids would not be "missing" if the parents simply STAYED in their hotel room, when their kids went to sleep.
It was completely, avoidable.
NO way, would I leave my kids, after they fell asleep, in a hotel room and then leave that said room.
NOT safe at all. To say the least.
How can your DH think, that hanging out until the wee hours, in the other hotel rooms, is more important than his kids???
Good grief.