We too plan to use only the photographer that Disney provides.
You do not pick your own. However, Disney Photographic services provides you with a portfolio of only 12 prints. These are prints that the photographer chooses. You can opt to by any of them at an additional price per print. The prices per print are quite reasonable, (I think). Included in your photography package is a low resolution CD. I hear it is about 40-60 prints. Since this is only a low resolution cd you can not print photos from it, you can only display them on your computer and e-mail them. You may purchase a high resolution CD of the same prints for about $1,000. I hear if you wait 3 years after your wedding date you can purch this same CD for only $99.
We have some friends and family that are really talented at taking pictures, so in addition to using the photographer that Disney provides, we are going to give our cameras to our friends to use as well. We wil than have these prints transfered to a cd and we will be able to print them anytime we want!