A lot of you are way too harsh on those of us who will not check a bag that may be too heavy for us to comfortably lift. I am the classic little old lady (5' tall, white haired, etc) that JS mentioned, and I travel with my camera equipment in a small roll on that I refuse to check now that we cannot lock our bags and theft is rampant. While the bag is small, it does not stow easily under a coach seat. It is heavy enough that I do need help lifting it up into the overhead bin and I have yet to be on a flight where someone didn't step forward to assist me. I have found that young ladies are especially helpful - while young men are not.

I hope I am never on a flight where I might need help from those of you who flatly refuse to help anyone. And yes, I always reserve the aisle seat - preferably right under my bag so if it falls out, it hits me and no one else.