So many lucky ones with good nappers!
My older DD stopped napping when my second came along (lucky me)...she was 26 months. She was never really a big napper, anyway (about 45 min at a time, usually) and she still doesn't need as much sleep as many kids.
My younger DD stopped when she was about 3. It was somewhat selfish on my part...when she took a nap (any length) at that point, she'd end up awake until 10 at night!! It was just too much...so we transitioned the nap away and she would go to bed at 7:30 and sleep until 7:30 (same AMOUNT of sleep as before, just all at once).....it took about a week of her being a bit grumpy by bedtime before she got used to it and then we never looked back!
My girls do still have downtime in the middle of the day (at 6 and 4), though. They don't fall asleep, but we do something very calm....read, color, that kind of thing....for about an hour after lunch.