I'm not a fan of the lower back tattoo. My ex-girlfriend had a shitty looking one of a flower and everytime I did her doggystyle I would have to look at that ugly thing. They are so played out. It's hard to find a girl that doesn't have one.
I'm not a big fan of tatts, but the best place is diffinately a subtle on on the small of the back, or a little bit lower than the belly button, a little to the side.