Actually a narrow (4-8", or somewhere in the middle) curl grip affect's the lat's better. Also a narrow curl grip BB row, directly into the lower abs each rep, hit's the lats well. A lot of very big men use this version over regular BB rows, with very heavy weight. (come to think of it, I think that was the way Yates whacked out his bicep with that grip..of course over abuse of 'roids can weaken the ligament/tendons of any one...after a period 'roids tend to targets the inserts of the biceps, pec's, quads...not to mention the internal organs of the body). BB row's, with a wider grip (elbows almost in a straight line with the bar) and bar touching the mid chest area each rep, hits the posterior delts, mid back and lower traps. Another exercise that hit's tha general area is chin's touching the back of the neck.
The straight and bent arm pullovers are outstanding movements to bring that wide sweep of the lat's, starting from under the arm pits, into play. Can work up to some vey impressive poundage with this exercise. Of course, if you have the potentional and the body frame for extra wide lats. Check your parents out. If mom's has super lats than odd's are you will.
Could try a 6-8 week cycle of GVT (10X10's) if you have tried everything else. Just pick one lat exercise and workout 2 to 3 times a week on that one exercise.Bent arm Pullovers,would be my first choice, but it's your selection. The lat pulldowns, chins, BB rows should all use that close curl grip. The biceps are also strongly affected with that grip. Good Luck.