very great hikes from one hour hike to several day hikes. most popular from easiest to hardest are that one must do are: bottom of lower yosemite falls, vernal falls, navada falls, yosimte falls, and half dome. Half dome will require a over night permit if you plan to stay the night witch i recommend doing. 16 miles round trip is hard to do in one day. permits can be found at the visitor center in yosemite valley. get ther before it opens as the permits are limited. Packs lots of water if your going to do the half dome hike