Did any of them plan or expect group sex in Las Vegas?

Do people think that anyone (well, I guess talking about Bob and Carol, here?) expected group sex to break out in Las Vegas?

As the movie flows, and I rewatched that scene again, albeit quickly, I didn't really see any sign that Bob and Carol had gone expecting that to happen. Perhaps they were open to it, but I didn't really see any 'leading' or 'seduction' to that effect.

Rather, it seemed to be Alice's very tipsy questioning of Bob that provoked the 'first we orgy, then we see Tony Bennett' ball rolling.

I had the sense that Bob and Carol hadn't seen the weekend as anything but a fun outing with friends, and the four of them crawling into bed was probably just a tad beyond the degree of 'liberation' that they had moved to.

Bob and Carol certainly, uhm, adapted to the changing situation more easily then Ted and Alice, but getting there sure seemed awkward for all of them.