Well I have narrowed it down since I originally posted...
Directly above the driver's head, I hear a tapping noise. Sounds like somebody tapping on glass. This appears to be happening worse at high speeds, but can be heard at lower speeds as well.
From the roof of the vehicle, and seemingly from the back of the sunroof, I hear a rattle or a popping. This seems to happen worse at lower speeds, and especially when going over bumps.
I have not taken my vehicle into the dealer yet to try to have the issue resolved. Haven't had the time. I plan on doing it as soon as the end of this week. If I find out anything, I will let you guys know.