About 90 minutes from Manteca via Highway 120, Yosemite Valley is a worthwhile day trip any time of year. The glacier-carved valley is framed by granite monoliths -- El Capitan, Half Dome, Cathedral Rocks -- and fed by waterfalls that peak in late spring. Each season brings a different character: wildflowers in May, warm swimming holes in summer, golden oaks in October, and snow-dusted cliffs in winter.
If you are driving from Manteca, take Highway 120 east through Oakdale and into the park via the Big Oak Flat entrance. Allow time for the winding descent into the valley, and arrive early in summer to avoid the worst of the parking congestion.