Yes I have. I know for sure that I want Pedro Calderon de la Barca's signature (if it exists and I can find it), George Orwell's, Oscar Wilde's, and Groucho Marx's. Yes I know, Groucho is not an "writer" like the others but he has influenced my life significantly. As for placement, it really depends on how the signature looks. But I'm wanting to do a quarter sleeve of some sort of the signatures.
As for pain, you really can't believe what other people say and attribute it to yourself. Everyone is so different with pain. I can't take pain very well, so it's fairly painful for me. For others, it's like nothing. It also depends on where you get the tattoo. Feet generally are pretty painful. But it a funny kind of thing. The second the tattoo is done you forget all the pain and immediately want another one. It's a horrible addiction.
Here's a picture of my tattoos. Please ignore the shoes. They were a last minute "Oh no! I don't have sandals and I'm getting a new tattoo!" buy.

Shakespeare needs a touch up.