Strenuous hikes
Half Dome hike
17-miles 12-hours with a breathtaking, dangerous climb holding chains on the majestic Half Dome at the end. This hike requires a permit for the final Half Dome climb.
The Clouds Rest Trail
12-miles 7-hours hike. The trail ends at a point higher than Half Dome. One gets a great view of the park as well as Half Dome from here.
I would recommend doing only one of these two hikes in a single trip.
Scenic viewpoints and Small hikes
Yosemite Falls
The lower falls are easily accessible with a short walk. The upper falls require a 6-mile hike. I only did the former.
Bridalveil Falls
Another gorgeous fall accessible with a short 10-minute walk.
Glacier Point
Glacier Point provides a great view of Half Dome for non-hikers. It is located about an hour away from Yosemite Valley and close to the south exit towards Fresno. For hikers, I would recommend doing Sentinel Dome or Taft Point; both are one-mile hikes with a starting point about 2-miles drive from Glacier Point.
Mariposa Grove of Giant Sequoias
Mariposa Grove has multiple hikes ranging from short walks to 7-mile hikes where one can see the giant sequoias. Due to time constraints, I only did the short hike here.
Where to stay
If you are doing Half Dome, then stay in Yosemite Valley the previous night to start hiking early in the morning (4-5 AM). Curry Village has the cheapest lodging, and the camps are located conveniently inside Yosemite Valley. Book well in advance.
The park is huge. Roads wind around mountains and hills. Driving inside the park can consume significant time; I would recommend planning for that in advance.