Seated cable rows are great for hiting the lower lats, and exercises such as bent barbell rows are great for overall back development, including the lower lats. You could also try V-bar pulldowns, concentrating on contracting the lats at the lower part of the movement.
The key to overall back development is to use a variety of back training exercises. The back includes quite a few different muscles, so a variety of exercises is necessary for complete development.
Good luck!