I am dying to get Thor a sister, but I'm waiting until his social skills get a bit better.
Right now, he feels entitled to sniff any passing dog's butt, but he gets all offended if they take the same liberties. I do think that's a big part of it, Thor can't have fun without me. I can't even go to the park with him and chilll while he plays - he doesn't like to run around unless I'm up and going around with him. Or he starts harrassing people with food and I have to call him away every ten seconds. I'm hoping that maybe in another year he'll be more playful with other dogs.
I'm also going to take him to obediance classes, which I think will be good for bonding, but I'm not sure if they will be a substitute for daily exercise, or in addition to. I'm thinking the latter.