Weighted pullups are KING for upper lat width, however, nothing, NOTHING compares to the pullover machine for absolute lat THICKNESS. For those of you who haven't had the pleasure of using a Nautilis pullover machine, I would highly recommend you try and find a gym with one. The isolation it gives for the lats is unlike any other free weight exercise, even dumbell pullovers. With the dumbell you often just end up working the chest and triceps more so that the lats.
yes, those nautilus pullovers are great. pullovers are probably the most underrated exercise. they destroy lats, chest, and triceps, all while expanding your ribcage and giving your whole upper body awesome shape.
for pure lat THICKNESS though id have to go with underhand grip, bent over barbell rows, heavy, with a pause at the top.
