If you love waterfalls, go to Yosemite in May or early June. The falls are at their peak due to snow melt. Several of the falls will be dry by late summer, including the 2,425-foot upper and lower Yosemite Falls, the tallest falls in North America (twice as tall as the Empire State Building).
There are several great views of Bridalveil Fall (620 feet tall) with its dramatic cascade over the canyon wall. In the late evening of Spring days, a rainbow is formed in the mist and can be best seen from the parking area next to the fall.
The ultimate waterfall hike is the Mist Trail. It starts at Happy Isles (shuttle stop 16). The 1.5-mile hike takes you to a close-up experience with Vernal Falls (320 feet). You will climb about 1,000 feet in elevation. About 1/3 mile from the top of the waterfall, put on your rain gear! The heavy mist will soak you as you climb hundreds of stone steps. At the top of the fall, you can continue to Nevada Fall and make a loop with the John Muir Trail or return the same way.