Glacier Point offers the best view of Yosemite Valley, hands down. The only view that rivals it is from the top of Half Dome, but to get there you need to hike all day and the view is missing one key Yosemite element: Half Dome! When looking out, here are a few things to note (from left to right):
The highest waterfall in North America, Yosemite Falls stretches 2,425ft from top to bottom. It is best seen in April or May when it is most full. Because the vertical drop is so long, it does not look like the water is falling very quickly because the wind often blows it sideways (but take a hike to the bottom of the Lower Falls and you will see just how powerful it is).
Clouds Rest looks much higher than it is because of the immediate drop down to the Valley floor (its peak reaches 9,930ft). You can hike to Clouds Rest from Tenaya Lake (7 miles one way) or Happy Isles trailhead (9.4 one way), where you would start to hike to Vernal Fall, Nevada Fall or Half Dome.
Likely the most recognized feature in Yosemite, you could stare for hours wondering how Half Dome was formed (see the Geology hut for explanations). Half Dome stands proud over the Valley, but if you wish to stand proud (and a bit exhausted) over it, consider Hiking to Half Dome (16-17 miles round trip).
Vernal fall is one of the more impressive and most-seen waterfalls in Yosemite. Many visitors take the short hike along the Mist Trail (you will see why it has been named that when you get closer to the waterfall) for some magnificent views of the waterfall up close, and the chance to see a rainbow in the mist.
A little further along the Mist Trail past Vernal Fall, fewer visitors take the opportunity to see Nevada Fall. If you have the time and the energy, you should extend your Mist Trail hike to include this powerful beauty as well.