"As far as which way to turn, if you're going to do all of them anyways, it really doesn't matter. Depending on clouds, you'll get a few better views of McKinley going north on the Parks Hwy rather than south."
^^^^^ This. Direction on the loop doesn't matter per se, but Mighty Mac seems to be more often visible going North vs. South. Conversely, other parts of the range are, at least from the road, more striking when heading South from Squarebanks. FWIW, there are a couple of different views of McKinley available on the drive into Talkeetna that aren't available on the Parks itself. 'Course, it all does depend on clouds.