A friend of mine has full sleeves. But the most painful spot for her was the top of her foot. It's "simply" the initials of her kids... but she felt that every hit of the needle was directly on a nerve.
The crook of her elbow was second most painful.
I would never get the top of my foot or hands done. I've heard those are super painful spots. I'll use the pain chart above as my faithful guide. : )