It is incredible how many people who live in the state of California have never been to Yosemite. It's closer to LA than San Fran, prettier than Mammoth or Big Sur and honestly a must do on the list of places to visit before you die.
I don't have too much to say about places to eat and sleep and drink because there is really only one place to go: a campsite. Grab your tents and sleeping bags and swing by the grocery to pick up your burgers and beer and just go make camp. From your site you can walk up to the the hikes, the river and any of the trees or attrations you want.
Just writing this is making me want to go camping again. And the only thing you really must do while you're there is get off your lazy bum and go sweat some balls on a hike. The last time we went we did a hike up the side of a massive waterfall and went for a dip in the small lake at the top. I forgot my trainers so managed to do it barefoot, but I wouldn't recommend that. Kit up and get busy.