The major texts we use for English II happen to have leadership as a common theme. It wasn't planned, but it works out nicely. We use Animal Farm, Julius Caesar, Lord of the Flies, The Prince, and Antigone.
The thing is, those are all kind of... well... dismal. And I've been trying to think of a work (ideally not one by yet another dead white guy!) that focuses on what it takes to be a good citizen and/or a good leader but carries a positive overall tone. The best one I've come up with is To Kill a Mockingbird, but (a) that's one of our texts for English I, and (b) it's still kind of discouraging!
Image thanks to demotivators.com