What a great trip. A lot to be packed into 5 days but well worth it. We did the three star package and stayed in Mestre. No problem. Easy getting back to the hotel via bus from Venice. Our tour guide Mario did a great job. It would be nice to be able to charge the optional trips via credit card as the guide only took cash (Euros). So make sure you bring enough cash. we didn't do all of the optional trips but the optional excursions to PISA and Venice at Night were worth it. Hotel Diana is very close to the Termini and the Metro.
A must do. The blue grotto and chairlift to the mountain top were incredible. Not a whole lot of time to shop. If you want to shop then stay a few days in one of the hotels. But this was a great day. The bus company picked us up at the hotel and treated us great.