I'm rather partial to the north shore of Lake Tahoe, where I lived for 16 years before moving off the mountain to Carson City in 1996. It's still only a 30 minute drive for me to get there. A favorite place of mine at the lake is Vikingsholm at Emerald Bay, but you can't get there during the winter months. I'm not fond of the south end of Tahoe, it's too much like visiting a big city compared to the rest of the lake. Anyway, there are great views to be found all the way around.
South of me, down Hwy. 395, are several more favorite places. Bodie Ghost town (closed during the winter), Mono Lake (the tufas are amazing), and the June Lake loop (fun for fishing). All can be visited and explored in a one day trip.
I've got to second the Grand Canyon and Crater Lake as well, both beautiful places to see.