It's fairly well known at this point that buildings stretched out east to west have the best passive solar orientation. I'm not entirely sure how this plays out when individuals pay to heat/cool their own units (I see your point about north facing units), but on the aggregate, it still makes for a more energy efficient building. Units in a multi-unit building are always gaining/loosing heat energy from the rest of the building. If you're talking about the desirability of having a sunlit room, then that's another issue, but this is definitely the most energy efficient arrangement. Besides, north facing units will get morning and afternoon sun 6 months out of the year when the sun rises and sets in the NE and NW respectively.
This orientation maximizes the southern sun in the winter while minimizing the morning and evening sun exposure in summer. Look it up if you don't believe me. One of the best professors I had in college was an expert on this stuff, and beat this drum EXTREMELY hard... I got the east-west orientation lecture at least 8 times, and there's plenty of science to back it up. This website I found with a quick google search briefly explains these same principles from his lectures.
http://www.ecowho.com/articles/6/The_importance_of_building_orientation.html