For adding thinkness to your lats bentover rows are 2nd to none with mabye the exception of T-Bars (old school jam a bar in the corner), however cables can target the back in many different ways, for example a wide grip palms inward really targets the rhomboids as well as the middle and lower traps, two areas where most people are lacking. Closer grip cables can really strech out the lats and improve the sweep. Your best bet is to incorporate both exercises into your training split. Also, switch your grip on the bentover rows, dont let your body get too accustomed to one form, an underhand grip will really target the lower lat. Don't be afraid to switch out the bent over rows for T-bars from time to time either.
if you really wanna crush the lats though, through a plate or two on a belt and hit the pull up bar!
damn i just repeated some of Rodja's post my bad...