Get a vertical monitor. Most applications make much better use of the real estate offered by a vertical monitor than a horizontal ones. About the only time a horizontal monitor is better is if you're doing something with photos or videos. Or games.
Consider how much more often you use your iPhone vertically than horizontally when given the choice.
+1 for vertical monitor. I had a 23 inch horizontal + and old 19inch which I turn it vertical. Best setup ever, you can read and takes notes, or you can code on the vertical one.
Trust me, vertical monitor does wonders, the entire word document at 150% is shown to you at the same time.