If you love Yosemite, you will like Sequoia/Kings Canyon, too, and they are less crowded. I think they also are a bit closer to you, but geography is not my strong suit. You can base out of Visalia if you want to avoid the high costs of the in-park hotels.
If you haven't been to Lassen, I highly recommend it. It's a bit farther (though not as far as Yellowstone!) but well worth the trip. Bumpass' Hell (yes, that's the real name) is unforgettable. We stayed in Red Bluff for our trips there. We were planning to move to a motel in a small town (maybe Susanville? not sure), but there was a fire, and it lost power and shut down. So we stayed the whole time in Red Bluff, which was supposed to be our "on the way" stop. When we went back a couple of years later, we just planned to stay in Red Bluff from the start.
DS '04 "Boogaboo"
DD '08 "Lilybear"