Best Way To Configure Shipping For A Monthly Club Product

What is the best way to configure shipping for a monthly club product? I currently have it set up where the product adds an addition to the regular shipping charge, but the problem with this is that I have a required option for the product, and weights can change dramatically between the available options. For some the shipping rate will be fair, others too high and others too low. Is there a better way to do this?

Any ideas? Does anyone have this type of product?