especially his loony charge directly into the Union artillery at GettysburgWe would be using Confederate currency today had Lee listened to Longstreet at Gettysburg. Lee broke his own, and a well-proven rule of warefare: choose the ground where you fight. Stuart left him blind.
I recall that after First Manassas, Southrons could have marched on Washington with little resistance. I think the armies were still feeling each other out; you know what they say about hindsight. Of course Mclellan had many more opportunities to capture the ANV, but never pulled the trigger.
Confederate forces were exhasted after Manassas and disorganized. It is unlikely they could have capitalized the situation, as their victory was mostly luck and a bit of home-ground advantage. Had they marched on Washington, the whole affair would likely have degenerated into mass looting and burning until a Union force could be hastened down to drive the Rebels out- there simply wasn't good enough discipline in the Confederate ranks.