We ended up hiking about 2.5 miles to the waterfall and then doubled back. We could have taken the loop route back to the beginning, but that would have added about 1.5 miles to the hike and we were hungry and hadn't packed food.
Overall, the hike was a had a good mix of uphill and downhill, changing continuously so that it never felt like you were at a constant uphill battle. But it was never flat enough to bore you. I liked it a lot and would definitely go back, as it was a great workout without ever really feeling like death. West coast hiking is also awesome because the trees are mainly evergreen so the scenery is beautiful and the trees kept us covered from the light rain (the trees made it feel like barely even a mist).