A little bigger than you want, but we have a saint bernard and he's low energy, terribly affectionate, doesn't need haircuts, doesn't wander, isn't overly barky (but will bark once at the door), and is just a giant love bug. We've had him here with babies and toddlers and he's NEVER knocked one over- he moves slowly and gingerly around them.
I think people discount the big dogs thinking they'll have a ton of energy and be wild, but my favorite dogs we've had as a family have been giants. Our Pyr was amazing, too.