Seconded about petroleum based products. In my experience I also find silicone spray more effective than Gummi Pledge at curing rattles and squeaks.
In my Targa most of these seem to come from the hatchback area - I spray both the rubber seal and the inside of the hatch which contacts the rubber.
Also worth checking the hatchback locking mechanism isn't rattling around - you access it by pulling the carpeted section of trim at the back of the car towards you. Behind that it will either be padded and solid or not and probably rattly.
Finally, I read on a forum somewhere about putting velcro patches in the corners of the roof frame to stop rattles and creaks. While doing this in mine stopped the rattles completely, it caused a water leak! Probably due to increasing the space between the glass and rubber seals. It goes without saying I swiftly removed the velcro!
