We took the Hidden Valley hike in early April and it was excellent, with very comfortable temperatures in the high 60s. Although the Park itself is fantastic, we found it to be a bit repetitive after a while, and not as diverse as other national parks (with much of the same flora and scenery throughout). This short one-mile loop packs a lot of the Park's highlights in one enjoyable hike. It's also always very nice to walk on a loop trail that brings you back to where you started without going back and forth in the same route. Highly recommended!