Near the home of an institution marked by tradition, it’s refreshing to see two Harvard Square shops with innovative face-lifts. Concepts (37 Brattle Street, Cambridge, 617.868.2001) and the Tannery (39 Brattle Street, Cambridge, 617.491.0810) have expanded their digs and proved that sometimes bigger is better. The Tannery’s “style you live in” mantra has been attracting stylish young shoppers who appreciate the store’s minimalist aesthetic that lets the $200 jeans speak for themselves. At Concepts, the sneaker-and-streetwear-loving crowd is eating up the fireplace in the center of the store, flanked by walls of bright kicks and quirky T-shirts and jewelry.