The Rue Nationale is the main shopping axis, lined with national chain stores. For more interesting shopping, head into the side streets — the lanes around the Hôtel Goüin (rue du Grand Marché, rue de la Rôtisserie) have good independent clothes shops, vintage stores, and one or two record shops. Rue Colbert is the antiques street. The Marché des Halles is the obvious destination for food.
For Touraine wine to take home, the Cave des Tours is on Rue Marceau and stocks a good selection of small Vouvray and Chinon producers that don't make it into the supermarkets. Bigot on Place du Grand Marché is the place for Loire chocolates and macarons de Cormery.