Plan according to the group as the rooms typically have a theme. I did one with my wife, sister, and her husband = all 80's kids. So we did an 80's themed room which was great for nostalgia and who could remember what. If the group is about the same age, picking a room they have in common can be fun, picking a room they don't know (like 00's theme) would suck. If the group is of mixed eras, then a room that can pull on info from across decades would allow all to contribute and be involved.
It was fun, a lot of fun. And a little bit irritating when you can't remember something and have to get hints from 'the watcher'.