Went up our traditional mother's day weekend, which is usually not very crowded, and was much more people than expected. But well worthwhile, Merced was 1-2 feet above flood stage and the falls were thundering, massive flows of water.
Went up for a day trip two weeks later, May 20th. Still decent waterflow, but not historic. But the crowds were oppressive, took almost a hour to cross the valley floor at 10am. The current road constuction didn't help. But the trails aren't that crowded. So we parked, hiked the eastern valley (Mirror Lake loop and Happy Isles) and had a wonderful time.
Can't imagine how bad the crowds were Memorial day weekend.