From Pisa you can have several activities to beautiful cities or to beaches. Firenze is less than one hour away by train (each hour at least one train). Lucca, Livorno, Pistoia, Siena, Carrara are all reachable by train or car trips.
Beautiful Beaches for Along the Tuscan Coast. The nearest beach is Marina di Pisa (12 Km). Tirrenia (15 Km). Viareggio (Liberty elegant town with long beach 23 Km).