As I said, the CDs I have been buying are full cast dramatisations of original Doctor Who scripts, and they largely feature four of the earlier incarnations of the Doctor (as played by Peter Davison, Colin Baker, Sylvester McCoy and Paul McCann).
Of those I can highly recommend the Peter Davison stories Creatures of Beauty and Spare Parts, two very good stores, and also the Sylvester McCoy story The Harvest. There are over 150 stories to choose from though, and I only have half a dozen or so, so I can't really recommend any more than that.
Of the book adaptations they have done of New Who stories, I've only heard The Stone Rose, which was given away free in the Radio Times a few years back, and that's okay.