Dont know about shrinkwrap from personal experience but I would think the less oxygen getting at the beans the better. Ive just invested in a vacu vin which uses a pump to give it an air tight seal. Im using it for Decaf and it is definitely extending its use by date.
With the rest of my coffee I just tend to leave it in the one way valved bag that it comes in and it seems to last ok for about three to four weeks post roast date.* :)