I've stayed at the FS Marriott before and used the Anaheim shuttle system. It was just a bit too far for me to walk after walking all day in the park (and this was pre-kids when I lived in San Francisco and was used to lots of walking everywhere). That said, it is technically "walkable," but I prefer to stay in the Fairfield just for location when I'm in Anaheim because I'm really never in the hotel for very long and the nicer digs don't do much for me. It isn't a hotel that you'd walk back and forth to multiple times for an afternoon break or anything, though.