Massive art installations
Tons of LA muralists, artists, and installationists are planning on displays -- including a 12-story harp installed from the ceiling to the street at 7th, and a street art challenge from the Mural Conservancy of Los Angeles.
Virtual reality demos and video games
Some of the leaders in the VR field are bringing their toys to the street, with promises that participants can (virtually, obviously) scale Everest, ride rollercoasters, fall from skyscrapers, battle mech warriors, and... throw whiskey bottles. Yeah, that's a game.
People watching, discounts, and exploring DTLA
Even if, somehow, none of this appeals to you, the idea of walking the streets of DTLA unhindered by cars, navigating in and out of staples like Grand Central Market as well as Downtown's new art galleries, restaurants, and stores (with discounts at many of them, ranging from 20% off fashion-y stuff at BNKR to priced-down bikes at DTLA bikes) while participating in a massive civic celebration should make you very excited that this is the city you live in. And if it doesn't... well, you may want to get checked out.