Angels' Landing and The Narrows are the most famous hikes and afford the most iconic views and photo ops. The former can be done easily within 3 hours if you are relatively fit and not scared of heights. I believe the Narrows takes 8 hours minimum but you can get a taste of it doing the Riverside walk.
Other than that, there were a few short hikes but the one that stood out for me was this really easy trail (like paved and flat) called the
Pa'rus trail that is near the Park entrance. The light bouncing off the river and mountains is magical at sunset.
