If you’ve ever picked a seat on an airplane only to find yourself with half the leg room as the rest of the row, you’ll appreciate this website. I found this site about 2 years ago after sitting in a cramped seat for 7 hours.
Since I have long legs, this site has been a lifesaver. It gives you a visual breakdown of most major airlines seat configurations by model of airplane, color coding the iffy seats yellow and the really bad ones in red. If you’re really lucky, you might find one of the green seats available on your flight, giving you the best seat in the house.