Aisle, Aisle, Aisle.
Sometimes I get lucky and have the whole row to myself and scoot over to the window for takeoff and landing. But the aisle is by far my choice, off the bulkhead.
I've been flying since 1981, and all those years taught me that I don't sleep well, if at all, on flights. For example, LAX-HKG flights I'll wander the 747-400 (upstairs and down) at least once an hour to keep the blood moving. I might get 1 hour sleep at the most. With UA001 gettng in early evening, I have no problem falling asleep in the hotel at a decent time.
I'm also in the habit of drinking a lot of water (Denver is a dry area most of the time) so there are a few trips to the loo as well.
On the return from SYD last week I left my exit-row aisle seat and grabbed a whole center row (row 60) -- I must have got a total of three hours of sleep. A personal record! That is, once I figured out how to avoid those &%$* lumps under the raised armrests.