We always go for the exit row. Not only is there more leg room, but in many planes, the seats in front of you don't recline, so all of your lap room is not stolen. On that same note, the seat in FRONT of the exit row is the WORST, because you can't recline.
My partner and I are both elite on Continental, so we generally get early boarding, which is super-important as usually when we fly, he brings his double-violin instrument case with him, which is not that big but it is very long, so it needs to go underneath the other stuff in the overheads. Most musicians refuse to check instruments, often going as far as buying another seat for their guitar/cello/whatever because airlines are evidently incapable of not destroying them. Southwest smashed a friend's irreplaceable 1931 acoustic guitar, even though it was in a case specifically designed for flying. It appeared to have been run over.
It's one thing to lose or "misplace" a bag with some clothes in it, but to destroy someone's priceless musical instrument is to potentially destroy their livelihood. Why don't they take just a tiny bit more care with luggage?
Boy did I get off topic!