If I have only a handful of items, I love the self-checkout lines. I've found that, at least in my area, the lines are much shorter in the self-checkout lanes, often time having at least one checkout completely open. I can complete the transaction faster than the express lane, and not have to deal with anyone else's ineptness.
If I have 20+ items, I'm too lazy to bother with self checkout 95% of the time.
