This building is a collection of famous attractions such as the Doge’s apartments, the dungeons, the Bridge of Sighs and the armoury. And for older children a tour of the secret passages (reservation obligatory).
Layout and collections - Palazzo Ducale (visitmuve.it)

An alternative to the famous Saint Mark’s Bell Tower is that of San Giorgio on the island of the same name, just 5 minutes from Piazza San Marco. From here there is a wonderful view of Venice, and without all the waiting.
Chiesa di San Giorgio Maggiore - turismovenezia.it

The island of Murano can be reached by boat in 10 minutes. Wandering around its narrow alleys, visitors will come across many craft workshops where they can admire glass blowing. The Glass Museum is a must.
Building and history - Museo del Vetro (visitmuve.it)

Visiting the island of Burano is a unique pleasure: it’s not crowded, its houses are highly coloured and it’s impossible not to find yourself smiling after walking along its streets. The island is also famous for its production of handcrafted lace.
Burano Italy, a Venice's island - Tour Guide and Official Site (isoladiburano.it)

This market has been in existence for around 1,000 years. Fruit and vegetables but above all fish have been sold here since the founding of the city in fact. It’s a true delight to wander around its colourful stands and discover local products such as castraure (baby artichokes), bruscandoli (hop shoots) and sparesee (green asparagus).

The Museum contains numerous relics connected with the history of the “Serenissima” and the Italian Navy: equipment, models, uniforms, but also real vessels. The most important is undoubtedly the Bucintoro, the Doge’s ceremonial boat.
Venice Naval Historical Museum | The Ship Pavilion (visitmuve.it)