Well, my DD (15) has been with the same boyfriend for almost 18 months and his family loves Disney. She's also been friends with his younger sister even longer. The family is quite well off (they own some national chain restaurants) and travel to Disney a couple of times a year. Unbeknownst to us, they invited our daughter to go to Disney December 31st-January 7th. They have already booked the flights and the rooms at the Contemporary. Now, we like this family and have no problem with her going (she'll get to go twice in 2 months as we're going in November!), but wouldn't you think they should have asked us prior to buying her an airline ticket? And we thought that once they knew she told us that they would call, but still no word.

Would you call them or just continue waiting for them to call you?
I don't think it that strange.
I have a teen that travels with a good friend all the time. They are uber rich, so booking a last minute trip to them is like going to the Motel 6 for a night.
Mom also travels for business every week, so literally has over a million miles in her account.
They will be shooting the breeze and decide they need to go to Disney. Since my child is like one of theirs, they go ahead and book an extra ticket. Since it is miles, if I say no, they just put the miles back in the account.
My child will come home and ask if they can go, I will agree, and my child will relay the info back to the other parents. We have a long enough relationship, like you do with the BF's family, that I completely trust them and they trust our child to be telling the truth that they asked us. It sounds like the other family also knows what a great young adult your daughter is and knew that the she would ask and let them know.
We eventually get together and talk about it, but it would not phase me one bit if they booked and then we talked about it. I always have the power to say no.
But since our kids have traveled together and had sleepovers, just like yours, it is a more relaxed atmosphere. We do things and are not offended if the other parent then says no. We know we wouldn't do things to each other for spite.
I also would have absolutely no problem with the girlfriend/boyfriend pairings. Sounds like the parents are responsible and have the sleeping situation under control.
Your daughter sounds wonderful and you sound like a wonderful mom for letting her go. You have a very lucky daughter to have friends like that and a wonderful family that allows her to enjoy the opportunities that come her way.