The trail to Fitz Roy (sendero al fitz roy) starts in El Chalten and passes through Lag Capri lake, Mirador of Fitz Roy viewpoint, Poincenot campground, Rio Blanco, and Laguna de los Tres. If your objective is to just see good views of the Fitz Roy peaks, you can probably just do the Mirador viewpoint trail which is about 3 hours return on an easy trail that only has an elevation gain of about 350 meters from the starting point. Check out the map on the El Chalten page for description of the trails and travel times. Also note that you already have some really good views of the Fitz Roy peaks while approaching El Chalten, so technically you don’t even need to hike or trek, but it’s definitely worth it.