I use to belong to the Gevalia coffee club, but I think we got to pick our own flavors. I can't remember...it's been a long time!
Personally, I wouldn't like to receive surprise coffees only because I have a pretty sensitive sense of both taste and smell. When I used to pick Gevalia coffees, I'd actually use their charts on acidity, body, etc. For example, I don't like highly acidic coffees, like the ones you get at Gloria Jean's. <img src="/images/graemlins/tongue.gif" alt="" /> I also don't like flavored coffees if they taste too artificial. I much prefer buying different types of roasts, and if I want flavor, then adding it with creamers and such.
For those who just love coffee and aren't really discriminating, most would probably love getting a surprise every month, though. <img src="/images/graemlins/smile.gif" alt="" />