I absolutely love screen, but I frequently forget a few even more powerful but useful features…
You can break screen up into two windows, both displayed at the same time. They call this regions.
I am actually writing this down, so I have a place to refer to when I forget next time.
CTRL-A S – Start new region
CTRL-A [TAB] – switch regions
CTRL-A X – Close region
And a few more tips here.