I usually don't check a suitcase, and almost never when I'm flying to my destination. I sometimes will check one on the way home though, when I'm more tired (jet lag, etc) and don't feel like hefting it into the overhead compartment. I once went to Scotland for three weeks with a carry-on and a personal bag, and, more recently, to Antarctica for two weeks with the same carry-on and personal bag. Mind you, I did have to carry the parka (no way it would fit in my suitcase!), but I made good use of its pockets.
My peeve would be people who try to cram an obviously over-large bag into the overhead bin. Only once have I been on a flight where the gate keepers actually made people put their bags in the little sizing thing by the gate -- more than half who were trying to pass their giant bags off as carry-ons had to gate check them. My bag is awesome. The gatekeepers could tell at a glance it would fit with room left over.