Stay at a budget family-friendly guesthouse like Hotel Casa Sant'Andrea (approx EUR70 per night family room). Check-in from 2 pm, leave luggage at reception if early.
Walk to St. Mark’s Square to explore landmarks like Basilica, Campanile, and Doge’s Palace. Many exterior views free, interior visits optional and cheap (~EUR5-10).
Book a budget-friendly family accommodation such as B&B Hotel Milano San Siro (EUR60 per night family room). Check-in from 2 pm, luggage can be stored earlier.