We do not present digital images on a CD or DVD. We use flash drives. Not only are they cooler and more cutting edge, but we say there are three major and practical reasons to make the move.
1. Optical drives will soon be obsolete. Apple was the first company to do away with the floppy drive and people thought they were crazy. Now they have done away with the optical drive. Even the new Macbook Pro won't have one. Their last version of Mac OS didn't even come on a CD. It was (and is) download-only.
2. Flash drives are *way* more robust. You can't scratch them, and there is no dye-layer to fade like a burned CD.
4. No need to worry about space. There's no 4.7GB limit. There's no need to play around with dual-layer discs which you also risk your client not being able to read on their soon-to-be-non-existant optical drive. The vendor I use has flash drives up to 32GB in size. Why does this matter? Well, we now shoot with a 36mp camera. Not long before you will too.
3. No expensive cases to order or design. I use a company that sells me wooden flash drives that are laser-engraved with my logo on one side, and the couples' names and wedding date on the other. Even with a custom wooden storage box it's cheaper than a DVD case from WHCC.
The *only* concern I ever hear from people is about write-protection... but I think it's a pretty silly argument. Your client would have to *really* screw up to delete or overwrite their images. And really, if they do, it's not much different than ordering a replacement DVD. Just have them mail the drive back, charge them a service fee to refill it, and you are on your way. But I've yet to have this happen. 😉 As a little courtesy, we include a README.txt on the root of the drive with some helpful information about using their print release if necessary, and what images are in what folder and what to use for what (as we provide different copies for print and web-use). You can also add some care info about maybe making a backup, or that just to be safe they can "copy" not "drag" the files off the drive if need-be... although I believe most computer systems by default use the "copy" function when dragging between drives.
Just a little food for thought!