This is interesting and DH and I vary in how we feel about it. We do WDW with my in laws a lot. SIL also owns
DVC. We have had a couple trips with all 15 of us. But other SIL, her DH and DD do not like WDW so they won't go again. We also have done trips with SIL who owns DVC, her fam of 5 and our fam of 5. We have had MIL and FIL...SIL has gone with MIL and FIL and not us. We, DH and I, have gone with just SIL and BIL. We go in 2 weeks with SIL and her whole fam of 5 plus 2 significant others of the kids (not kids really) and MIL and FIL and DH and I...not my 3 kids (not kids really...20 somethings but they couldn't come).
So we have shared and we have gotten separate. DH likes separate. SIL likes separate. SIL uses her points to book her own rooms. I use mine to book MIL (they paid to use). It's cheaper to book us a 2BR instead of a 1BR and a studio or even 2 1BRs. WHen the kids come, then I might get a 2BR for us and whatever MIL wants for them (she likes a 1BR). Though when the kids were young we did all stay in a 2BR once and it was just fine. And we took SIL to our HHI resort, we own at, and stayed in a 2BR together for 3 nights. That was fine.
The upcoming trip I have a 2BR for 9 nights for MIL and FIL and DH and I. I think it won't be bad because it's just 4 of us. ANd I got lock offs so we can opt to keep them locked off. But we won't. We might have some...um...moments. But overall it should be fine. It would be more problematic if we had little kids as then there may be issues with how we discipline our kids and all that jazz. BUt just us 4 adults in a 2BR...should be fine.
I also bring my mom a bunch and we always share a villa. We have even done studios, her and I or her, my 2 DDs and I...and I will say I won't do a studio with her again. I'll book a 1BR for us 2 or 2BR for us with DDs. We both need our own sleep space, TV control and whatnot. She likes to stay up late with light on doing crossword puzzle and loud TV while I like quiet TV and dark room around 10-11pm. She gets up to use bathroom like 4 times through the night and it wakes me.
DH has requested we don't share villas with others anymore. We have a lot of points and are cutting back our trips so I can oblige his request.
We did share with some friends one time and that did not go well. They were in their room a lot and on cellphones and not super involved. We know to just go separate when vacationing with them. Actually I prefer not to share with folks I am not really close to. We did a competitive sport with our kids where we had to travel and many folks liked to share, even cram in to make the cost super cheap. But I prefer privacy and not a fan of sleeping in same room with ANYONE but my DH, kids and mom. Sometimes that extends to a whole condo or house...just want to do things your own time and way. Go to bed the time you like, keep the thermostat at the temp you like, watch TV how you like, eat and drink as you like, walk around dressed as you like.