I'm a big guy. I'm also a tall guy. I'm talking lumberjack without the flannel, folks. That combination spells P-A-I-N in many areas of human endeavor. For instance, it's a little-known fact that "big and tall" stores are really "big OR tall" stores; if you're both, you're often out of luck. I've been met at the door of such establishments with a pitiable glance and a sotto voce "We won't have much to fit you."
As you might imagine, air travel is a challenge all its own. Over the years, I've learned a few tricks, including asking the attendants to let me know if any pairs of adjacent seats are empty. Even so, putting my 6'5" frame in the typical airplane seat is comical at best, and painful at worst. I once had a fellow traveler who attempted to excoriate me for putting my backpack in the overhead bin, instead of under-the-seat-in-front-of-me; I just shifted in my seat, held up one of my 13EEEE feet, and he walked away grumbling.
Enter SeatGuru. I love this website. No, strike that - let's go big and say that I LOVE THIS WEBSITE! It's ridiculously simple; you toss in your airline and flight number, and it coughs up an annotated seatmap of your plane. Not only does it identify seats with no space to recline or fixed armrests, but it goes into those little details that business travelers love, such as which seats have AC (or USB!) power. (That last point is particularly important on intercontinental flights...)
Between SeatGuru and my frequent-flyer "choose your seat" options, my air travel has been made much more comfortable - or, at least, far more bearable.