The DEPTH of your space is the most critical element to consider when positioning yourself in front of an audience. The only dimension that adds value is depth. Height and width are accepted instantly, but depth perception requires concentration and therefore creates an enduring effect.
For example, you can watch a movie on a big screen (cinema) or on a small screen (TV) and you can adjust to the height and width of that venue immediately. The issue that matters most is the depth of the action — that is, what’s happening ON the screen.
Since depth has visual value, then you can use the dimension of depth to create impact. A move TOWARDS the audience signifies something different from a move AWAY. Likewise, any move from side to side in front of people will have little effect. This is why crossing from one side of the room to the other is hard to justify, especially if the audience has no clue as to why the cross was made.
But depth is an automatic perception for everyone. So, once you select the area of the space to present within, use the depth of that space to add value to your words by moving towards or away from the audience.