In my experience, as others have said, the shoulder is probably the least painful area to get tattooed, to the point where I also wouldn't call it painful. I'm halfway through one right now which runs from my chest/armpit over my shoulder and upper arm, and onto my back, and the shoulder was the only real reprieve. The armpit, chest, arm, and back (in that order) were certainly painful to varying degrees, even if they were tolerable.

I also got one not long ago, a round dial about 3 inches across, on my quads a few inches above my knee that was exceedingly painful, an area where the pain charts seem to suggest is not usually painful.

The most painful for me is when when the outline is done and they go back to do the shading/texturing and the skin is already angry. That's a good time to stop if the tattoo is sufficiently large.