Best of all, it's just two hours from San Francisco.Light coming through trees on a walkway in California's Armstrong Redwoods State Natural Reserve.Credit: Melissa Kuhnell/robertharding/Getty ImagesKey PointsLess than two hours north of San Francisco, Armstrong Redwoods State Natural Reserve is home to towering trees hundreds of years old.Hike among the giants on the Pioneer Nature Trail, which takes you to the 1,400-year-old Colonel Armstrong …