We cannot stress enough that audience size matters! We have all been to a presentation where we cannot see the screen, or it feels really crammed.  Your view is masked by a huge speaker right in front of you or its blasting in your ear, yet people at the back are complaining because they cannot hear.  Take sound for example, in a long thin room we would look at a little and often attitude, this means lots of speakers at lower volumes giving subtle lift along the room, A big stage event would typically have arrays of speakers at the front projecting out to give focus to live bands and music.  For vision the sizes could make the difference between using a single or multiple screens, and perhaps relay screens at the back of the room.  We often get told that a 42″ TV will be fine as that is what their TV at home is and they can see it in the front room, we do remind people that most audiences are further than 6m from any screen and that that is about twice the distance of most living rooms!