I did the loop trail. From the bridge at the parking lot it was 3.5 miles and took me 1.5 hours. The waterfall is lovely and just 10 minutes up the trail. If you do the loop, start on the EAST SIDE across the road from the parking lot. I made the mistake of starting on the west and doing the loop counterclockwise (though this is the logical route). If you start from the west, once you cross the road to continue the loop (about 1.5 miles in) there is a very steep part of the trail that goes straight up for about 0.5 mile - 300 ft elevation gain. If only I had started the opposite way there is a much more steady, meandering trip up.

I haven't done the out and back portion of this trail but it looks like it would be about 5-6 miles round trip if you continue all the way to the connecting southwest trail.