RaggTopp is known for their convertible top cleaners and protectants. 303 makes a couple products as well, but I don't have much experience with either.
An APC would work well if you didn't have the 303 or RaggTopp available.
It's important to note the importance of using a stiff nylon brush. Wet the top with water, then wet with chemical. In a tight circular motion, scrub the top with your brush. You should see dirt foam up. Rinse the dirty foam away and repeat until clean.
The best chemical, if applied with only a rag, will not do a good job of getting into the texture of the top.
Thanks Applied Colors that is my only option because I am doing the car Thursday. Also Thanks Jakerooni and Shine I will have to order one of those soon.