Sorry for the late reply ScottH454,
You can add as many spine bones as you would like but to give a good overall feel of transforming the bones I usually have values either evenly distributed throughout the bones i want to manipulate at a low value or have give a slightly less alpha blend value to the bones that are higher in the bone chain because it never takes that much motion to make the bones that are lower in the chain to move allot when the root bones are moving.