If you want a wide set of lats, why not ask the man who helped Batman spread his wings?
Walter Norton Jr. trained Ben Affleck for Batman v Superman: Dawn of Justice with special focus on the actor’s back.
“We had three pullup days a week, usually paired with other torso work or squats,” he says. Affleck rotated types of pullups, including parallel-grip (palms facing each other); alternating grip (one palm away, one facing); and chinups (palms facing you).
Intensity varied, too, as he sometimes worked up to heavy sets of just 3 reps and other times did higher reps with slow negatives (taking several seconds to lower his body to the bottom of a rep). It worked!