Everyone wants digital copies so I do provide them for a price. I have a unique situation though. My family is in the printing business (have been for 25+ years) and my studio is in their shop so I think we provide a nice high quality one stop shop type of service. We can even print and bind our own photo albums (hard bound too) right in the studio! To make my CDs higher quality we also print images along with their name on the CDs.
I think since all of the machines are all in the shop and my clients see that and they see the sample prints on the table along with the book that stears them more towards prints. I believe if they can see it and touch it they will want it more.