No Whedon tattoos (yet!) but I do have other "fan" tattoos (one from a book, one from a video game). I don't regret them one bit!
For placement ideas, I'm going to be boring and suggest to get your first few tattoos hidden. But again, it really depends on what you want to get.
If you do get a quote, just a little warning. Many people think they are the most simple tattoos so they can't get screwed up. But I would still be careful about the artist. Since writing is so thin, if the tattoo bleeds out there are more chances of the lines looking really bad (vs a drawing for example where a bit of bleeding out is usually not too noticeable). My quote tattoo's ink spread quite a bit because the artist was too heavy on the needle. He was a fairly well known artist but I just happen to have fairly thin skin so he went in too deep. I still love the tattoo, but if you're a perfectionist it's something to look out for.