This is at least two distinctly different roads. Both worthwhile, but each with its own character. First, you have the section from Big Oak Flat to Lee Vining. This section approaches and passes through Yosemite NP. What can you say? Some of the most dramatic scenery in the world. Everyone should visit, and on a nice weekend in the summer it will seem that everyone is. Traffic can be heavy, and speed limits in the park are low - and enforced. Not only that, most of your fellow road users are so gobsmacked by the scenery that they might as well be texting on their phones because they sure aren't paying attention to their driving. You've been warned. Take your time, get off your bike, look around, take some photos. You'll continue east over Tioga Pass, the highest pass in the Sierra, and drop steeply down to the town of Lee Vining.
As you approach the junction with Hwy 395 there will be a gas station on your right. The deli inside is called the Whoa Nellie Deli, you will be making a mistake if you don't eat lunch there. Seriously. The wait is worth it. There are always loads of CHP around Lee Vining. You'll see them eating their lunch at the deli too.
As you continue east from Lee Vining and south of Mono Lake you will encounter the second part of Hwy 120. You'll climb through the big conifers on a gently sloping pass. There are a couple of places where there are great overlooks with views of Mono Lake, and while you're sightseeing be careful of where you put your wheels. If you go a little bit beyond the gravel shoulder the sand can be quite deep. Ask me how I know. Continuing eastward up and over the pass you will find yourself in the semi-arid west of the cowboy movies and it's spectacular.
One poster mentioned the bumps as you approach Hwy 6, and that's kind of like calling Moby Dick a fish. These are great big old whoop-de-do rises with maybe 40 to 80 foot elevation changes that happen fast enough to get your wheels off the ground over blind crests. It's like God's own rollercoaster out there, and while it's fun, it's not without considerable risk.
Stop and have an ice cream at the little gas station/diner/store in Benton get out of the hot sun for a few minutes before continuing your journey.
Almost endless excellent twisties, who could ask for more?
Stunning scenary and a selection of great corners make this a fantistic motorcycling experience. The highlight for me is round by Mono lake great sweepers and the giant field of redwoods, loved it! Watch out for the bumps by Highway 6