If you want to work your lats you have to do chins and pulldowns with a medium or close grip not wide. The narrower the grip the more stretch in your lats you get and greater activation. Also neutral grip or palms facing is also better.
Best way to do chins is shoulder width, neutral grip and arch your back so your chest is high. Personally I'm not a fan of cable pulldowns, but I love the shit out of two machines: the old nautilus pulldown where you sit facing away from the weight stack. It has a neutral hand position and is a medium width grip and the stack goes to 350. The hammer strength pulldown the dorian made famous is also very nice.
Thickness wise db rows should do the trick if done correctly. Try doing them two hands at a time, there is a pic in Arnolds BB encylopedia of him doing these. Stretch at the bottom and pull your elbows back and feel your shoulder blades come together. BB rows(I like yates rows where you are a little more upright) are good cause you can use more weight.