Assuming you are down by the overlook stairway after crossing the three bridges:
Taking a right is the shorter climb and the one I usually ride. You can go either way here and still get to the same place up top. I try to avoid riding up the trail that goes beneath the overlook (the straight/left option) during peak riding hours since it has more blind corners and is a fast downhill. This intersection should have a flex post with direction arrows unless someone pulled it out.

Assuming you are at the top of the hill at the 4-way intersection:
I typically ride the upper north loop in a CCW direction but either way is good. There is a map with a "you are here" indicator at that intersection but no flex post with arrows.