I have the Intuos3 6x8, and I would totally recommend it. The size is good for most desks, the quick buttons on it are great and can be configured to whatever you want them to do, or even be disabled, like the slide strip on mine, I turned it off because I kept brushing over it on accident and zooming into some weird place on my image.
The pen is nice too. Has a good balance and grip. I disabled the button on it as well because my big meaty paws kept hitting it at the wrong time.
I used to have a graphire as well, and I can totally tell the difference between the two, and as long as you can afford the cash, definitely go with the Intuos.