This writer has some tips on finding the best seats on a plane, but there’s an apparent bias:
Middle seats tend to be filled starting from the front of the aircraft and moving toward the rear—which means that if your flight isn’t full, you’re likely to get an empty seat next to you if you request an aisle seat in the center section in the back.
…I love 767s because there’s only one middle seat per row. This means that your chances of getting one are less than on any other two-aisle aircraft: A 767 can be 86 percent full before anyone gets stuck in the middle. Two-aisle planes tend to give you bigger seats, more legroom, and larger overhead bins than one-aisle aircraft.
…Unless I’ve achieved my personal nirvana of an aisle seat in an exit row, I always ask the gate agent if a better seat is available. Preferred seats (e.g., aisle seats up front) often open up at the gate because the elite-level or full-fare passengers who were occupying them get upgraded at the last minute.
Emphasis mine. Note that there’s an apparent assumption on her part that a) middle seats bad and b) aisle seats nirvana, for everyone. But why would I ask for an aisle seat when I don’t like aisle seats? I prefer windows, a word that doesn’t appear in the article. I actually almost prefer a middle seat to an aisle, because there is one less person to have to let out during the flight, and I’m not constantly getting jostled by passengers or flight attendants walking up and down the aisle. The only reason, to me, to prefer aisle is for safety (get out a little faster, unless you’re in an exit row), or a desire to get up occasionally and walk around (either for leg stretching or nature calls). My preference is to just cocoon at the window, where I can look out, and not be bothered by anyone else’s needs.
Yes, obviously, if you like aisles, then a two-aisle airplane is preferable. But if you prefer windows, wide-bodies suck, because they provide the lowest window-seat/seat ratio in the sky. My favorite plane, actually, is any variation on the old DC-9 (nowadays B-717 or S-80), because with only five seats per row, forty percent of them are windows.