You've been conditioned to work full screen because of the fact that Windows ties the menu to the application or document window. Which means you have to spread your window as wide as possible to get all your menu selections, usually with the result that you have gobs of wasted space on either side, or you're less efficient because your eye has to track large horizontal distances (there's a reason printed material is set in two or more columns above a certain page size).

I recommend you try resizing your windows to a width your eyes feel is comfortable and let your windows overlap. I think you'll find after a week or two, you'll find you can work longer with less eye strain, and also feel more "in control" of your environment because you'll have windows from other apps in the background, being picked up by your peripheral vision, thus giving you a sense of "location" regarding where you are in relation to your other programs.

Just some friendly advice from a Mac user who went to Windows because OS 7 sucked and a Quadra 660 with 8 MB of RAM was a joke running it, and who came back because the grape G3/400 iMac running OS 9 was wicked fast and wicked cool.