I have a Boxer as well as a Yorkie (Tyson). Unfortunately he won't play with the little dogs, so every so often I'll put him down (only because he's trying to jump otherwise) and he's out there running and playing with them. It's a prety funny sight to see the little guy chasing Great Danes and other huge dogs. I will say it's a good workout for him.
Hopefully someone will have an answer to your question...my little guy is a social butterfly. I don't know if that's a good thing or not.