the windshield is a common leak point. but yeah, the hunt for a leak can be a pain. I've had success with sprinkling baby powder around and using the garden hose to find a leak. the water will make little tracks through the powder that can be tracked back towards the source.
my least favorite leak was at the top of the windshield that dribbled down inside the A-pillar and dumped out onto the floor near the carpet.