Groveland is a gateway town, not a destination in itself, but it has enough to fill a half-day before or after Yosemite. The main street (Highway 120) has a well-preserved Gold Rush-era character: the Iron Door Saloon occupies an 1850s building with original cast-iron doors; the Hotel Charlotte dates to 1921. Walking the few blocks of Main Street takes 20 minutes.
For those with more time, the ghost town of Second Garrotte is a short drive east and gives a sense of how quickly mining camps rose and fell. Hetch Hetchy Reservoir — the flooded twin of Yosemite Valley — is an hour's drive into the park on Highway 120 and makes an excellent day trip for visitors who want Yosemite's scale without the summer crowds.