I visited Forest Dunes and the loop last summer and found it to be one of the most interesting and creative examples of golf course architecture that I had seen in a long time. I think it's a really difficult idea to execute that Tom made look really simple.
I've been thinking back on this comment and the course for a few days and think this really sums up the Loop. I almost think that it was executed so well, that maybe some people aren't giving it quite the credit it deserves because it came off so well.
I kind of feel like 5B/13R and 9B/9R really exemplifies that too. It seems like they nearly come in at the same direction. The green works well for both of them, but I can't imagine how difficult it was to not come in nearly opposite on every hole.
For some examples of holes I liked both directions:
4B/14R, 5B/13R, 7B/11R!, 12B/6R
Some that I loved from one direction and not the other :
6B (loved)/12R (didn't love but that may change with more plays)
13B (didn't love)/6R (loved it)
Josh, I agree with your and Bill's comment that Tom and his team made the Loop's difficult design concept look simple. I think he has said elsewhere that designing holes that approach from opposite directions, 180 degrees, would have been easier--out and in and easily reversible like the Old Course. The Loop has greens that anchor holes approaching from ~180, ~90, and--thinking back to 10th grade geometry--some acute and obtuse angles.
I think 9 is the only hole that basically has an approach ~from a single direction for both holes. 5B/13R serves a slightly uphill par three, 5B, that plays ~from North-South, and 13R is a par 5 that plays ~from East-West over flattish ground to an elevated green surface with a backstop that covers almost all of the width of a wide green. That's a great green, really fun to play from both directions.
+1 on your choices of holes you liked.