Google Maps provides a route from the San Francisco Bay Area to Yosemite National Park which runs along 580 to Highway 120. I find this route to be intolerably populated, unattractive, and often ground to a stop due to accidents or sheer traffic volume.
On a recent drive back, when I found traffic along 580 into Tracy at nearly a standstill, I cut north through the Delta and up to Concord. The contrast between the packed 580 versus the desolate back-roads was amazing.
Earlier, when Highway 120 led into Oakdale, I found that by cutting a single street North yielded a road which was almost entirely unused, had only the occasional stop sign, and featured beautiful views of fields and smelled of grass and cows instead of exhaust fumes.
According to Google Maps estimates, the standard 580/120 route only saves around 40 minutes versus a much more leisurely, scenic, and enjoyable route along Highway 4:
The standard route (183 miles, 3:50)
Alternative route via Highway 4 (187 miles, 4:29)
120 to Stockton via Valley Home Road at Oakdale, Highway 4 to Marsh Creek Road to Walnut Creek to Highway 24 (188 miles, 4:37)