I'd say try a border collie as sometimes having a big dog and a small dog doesn't end too well for the small dog if someone disagrees with the other ... I love my collie, she nicely rounds out our group of dogs with her intelligence and constant good humor. She bushes nicely, is frighteningly obedient, perfect in the house or on the farm, is a good watchdog, is not high strung, is great with people and dogs and we have used her as a lurcher in a pinch as well.
just my .02 cents ...