I used to ferment it out for 7-10 days, but recently I have been going 2 weeks (or longer if I'm busy). I bottle condition all of my beers and I've noticed a huge reduction in the amount of sediment in the bottom of the bottle if I leave it in the fermenter for at least 2 weeks.
With a 10 day ferment previously, the airlock would have stopped any noticeable activity, but when I racked into bottles it was still hazy. After conditioning, I would end up with a few mm of yeast sediment in the bottom of the bottle, which is too much (the last few tablespoons would be either super-turbid or discarded).
With a 14 day ferment (I don't cold-crash, this just sits in the utility room at 20°), the airlock still has no activity, but when I rack the beer, it is crystal clear. There is still suspended yeast that allows it to carbonate in the bottle, but this time, I get less than half a mm of sediment in the bottom of the bottle and I can normally get all but the last few mm out of the bottle without any sediment. I get more (and clearer) beer by leaving it an extra 4 days in the fermenter.