Since you write, I want to ask you, how do you feel the 15" is for side-by-side? One side is what you are typing, the other could be browser with research or PDF or anything.. how do you feel about the comfort of this vis-a-vis say, an iMac with 24" display but relatively smaller jump in resolution ?
On my 13" MBA, split screen makes the web browser too narrow, and sometimes my own document becomes too narrow - too vertical.
On top of that, on a desktop, this 13" makes my neck craned downwards all the time, and I do find myself hunched into the desk often. I am thinking the 16" would help me keep myself straight ?