I searched for "suite" in the title of posts in this forum, and found these threads which should be helpful, if a little dated.
Bottom line is that you'll probably need a 2 bedroom suite (which in some cases is a 1-bedroom suite with an adjoining room) because of occupancy limitations. This will likely cost more than 2-3 regular rooms. My recommendation is to stay at an all-suite hotel like the Venetian/Palazzo or Delano, because the rooms are big, you can entertain, and they're not that expensive. I suppose you can get 4 into a two-queens suite, but they probably charge you something like $30/night for each additional adult beyond the first two (also the 2Q suites are usually a bit more expensive than the 1-King bed suite).
I had 15 at my bachelor party/stag do in Vegas ~2.5 years ago, we stayed at Palazzo. And we actually never really spend any time socializing in the rooms.

Looking for Suite for 7 on Center Strip
Palms Place - Suite for bachelor party weekend?