Before purchasing my first digital camera this past summer, I always took about 20 rolls of 24-exposure film with me on cruises. I figured that 480 shots would be plenty, and invariably I didn't even use up all 20 rolls. In addition, many of my printed photos turned out to be "bombs" (read, "why on earth did I take this shot?" or "what the heck is this?!")
So I bought my Olympus digital (on eBay) with a 128MB xD Picture Card, and took it with us on our 12-night Baltic cruise. I didn't take a backup camera, only the digital. And I had to take a cram course of manual-study in order to get it to work, since I'd never used one before. Now on a vacation that included such ports as St. Petersburg, Helsinki, Stockholm, Copenhagen and London, you'd think that a person might take a lot of photos. And I did. But as I approached the card limit of about 165 shots which showed on my monitor, I started viewing my photos and erasing those that fell into the "why on earth?" category. And I was amazed at how many "great" shots fell into this class.
Bottom line: I ended the cruise + 2-night London stay with a total of 192 frames, more than I expected but far less than I would have thought I'd bring home from a 14-day vacation. During that time, I probably erased another 100+ shots. And by later culling out even more shots I really didn't want or need, I ended up printing (@29 cents per print) only about 140 of the 192. That's a lot cheaper (and more sensible IMO) that printing 20 rolls (= 480 shots) and eventually storing them in albums and/or throwing away many of them. And I didn't even reach the limit of frames the card would accommodate. I simply stopped at 192. For all I know, I might been able to take many more.
Jack (a Photography Dummy)