In my Altima, since it's still under warranty, and also since I negotiated free changes every 5k miles from the dealership.. 5k miles.
In my Fusion, I've historically always done 7,500 mile OCIs on whichever oil was in it (usually a blend of conventional and synthetic on a Motorcraft filter). This time, however, I'm stretching it to 10,000 miles, since it's got Pennzoil Ultra Platinum in it, and a Fram Ultra filter on it. I will be doing a UOA on it after the change, too, just to see how the engine held up to the extra 2.5k.