Specifically, something that tries to look at them less as mythological figures and more as actual people, I love history but I have to admit that I know fairly little about my own countries history when it gets down into the details and I would like to change that
American Revolutions by Alan Taylor is a good history of the American Revolutionary period from the Seven Years' War to the Jefferson presidency, without being drunk on American exceptionalism.
Not strictly about the founding fathers, but seems like it's down your alley.
Houlton's Unruly Americans and the Origins of the Constitution and Forced Founders portray most of them in quite a negative light. Only looking at specific aspects of policy, but still looks at them through something other than the national myth.