Wide grip pull-ups x4 6-10
(These are much better than lat pull downs,they add thickness and width) Add weight when you can do 12 bodyweight reps.
Deadlifts x3 6-10
(Use good form or you will snap up your lower back).
Bent over rows x3 6-10
(This really adds thickness to your middle back).
One arm dumbbell rows x3 8-12
(This sample back workout is guaranteed to build a aesthetic back in conjunction with a good diet.).