I used to have a Bamboo and liked its size. I lost the pen, so bought an Intuous Pro Medium that I use with my 15" MBP plugged into a 30" ACD. Using the entire useable area on the Medium mapped to the 30", it actually feels too big to me *the amount of arm movement needed. I remapped the workspace on the tablet to cover BOTH my 30" and my MBP screens, which are stacked vertically, and it works much better for me.
The moral of this story being a much smaller area than the Medium (it ends up being like 2/3 of the usable space) was more comfortable for me on a 30" ACD.
However I think it depends on what you're doing and your personal style. People used to freak out when trying to use my mice which were always at full speed ahead. Never understood why people wanted to pick up and drag their mice around using their whole arm. But hey different strokes right?
