I use to have 5 19 inch screens span across the bottom and it was really a waste of space although it looked pretty nifty!

I thoroughly enjoy my setup now which is 3 19 inch on the bottom and 2 17 inch on the top. If I 5 box'd I would upgrade for a 3 17 inchers on the top. Going any bigger for me would hinder more than help, you need everything close