The closest entrance to Yosemite Valley is on State Highway 140, east of Mariposa. That's the best way to enter in the winter. You can see more of the National Park by driving north from Fresno on State Highway 41.
I was wandering through Yosemite National Park looking for Fall color. There wasn't much yet, but this view, showing the weather-warn walls and the height of this massive rock formation, made the trip worthwhile.