Vernal Falls feels so much larger than its 317 feet. Unlike Bridalveil Fall, Vernal requires some sweat equity and cannot by viewed from the valley floor. The easiest path is a well paved trail from Happy Isles Nature Center. The Vernal Falls footbridge is a 1 mile, mostly uphill journey with some spectacular views. However, I recommend getting to the base of the waterfall by walking the aptly named Mist Trail. Although this trail closes in the winter due to possible rockfall and slippery conditions, many visitors took this path regardless. Given one of us insists on following the rules, we committee to a strenuous 4 miles uphill hike around the winter route. At least we got a workout. Plus, we were so tired after we reached the Vernal Falls that we took the closed Mist Trail down anyway and it was worth breaking a few rules.
As is true for all waterfalls in Yosemite, the ideal time to visit is in late April to early May at peak flow secondary to glacier melt.