Hey Man,
Your routine is almost perfect for a general back-attack. I would suggest mixing it up with starting with chin-ups, then deadlifts, and from there, switch it up weekly with the other exercises. Chin-ups are the best exercise, imo, for development of the lats, while deadlifts are the best mass-inducing exercise. These two are also the most stressful and taxing of the back exercises, so I recommend getting them out of the way first, while you still have maximum energy and strength. I would always do chins before deadlifts, because chins is generally the hardest exercise for most people - plus you'll be more inclined to try and pump out another 5-10 chins /before/ you do deadlifts - generally not after!!
I used Arnold's Enc.'s advice and aim for 50 chins each back workout. It takes me anywhere from 5-10 sets. Give it a try, you'll see the difference and your lats will grow from top to bottom.