I use tablets regularly. The mouse is like drawing with a bar of soap. I even like tablets for non-drawing applicatons. It just feels more precise.
I would suggest you coinsider NOT getting the larger tablets, whether you draw or do not draw with them. Think about it... How do you usually draw? With your hand and wrist, or with your whole arm? If you are doing digital media, you can zoom in and out of the image. Your drawing movements are probably confined to a medium or small area.
I've used jumbo sized tablets and they were horrible, you are constantly reaching and it is uncomfortable and awkward. A 9x12 tablet is probably fine. Don't think of the tablet as having any correlation to the size of the media you are working on, just think about the size of a comfortable drawing gesture.
i suggest you go a computer store and play with some different sized tablets, since the Wacoms are expensive, (especially the big ones) so se if you can test-drive one.