My guess is that most of the people here have played a Castlevania game - it's a very long-running and popular series, and deservedly so. If you want to take your gaming hobby seriously, it's one of those franchises you need to have some familiarity with.
Personally, I have Super Castlevania IV for the Super NES, and I'd highly recommend it if you can get a copy. I'd assume it would be available on the Wii VC. Symphony of the Night for the PlayStation (PS1) seems to be the most highly regarded installment, though I haven't played it personally. I can't comment on the newer games, though.