I prefer having several medium sized cards, which I rotate between at regular intervals.
This has the effect of breaking up my shots into smaller groups and decreasing the risk of losing a large number of shots. I don't worry too much about it though, as I have never actually had any corrupted cards, but I know that is a risk so I try to minimize it.
I also format the cards after uploading my images, which should lower the risks a bit as well.
This is not directly related, but I also recommend using higher speed (Class 6 or higher) cards, simply because it greatly speeds up the upload process.
Also, as far as cost, it is almost negligible, so if I were to want, say, 32GB of memory, I'd prefer 4 8GB cards over 1 32GB card (same speed), which both come out at roughly $70.