Re: When in Rome...
I absolutely love Italy too, and am very envious.
Most members here have given good advice for you to follow. I just want to add some more. I know that Venice is now considering, or already started, charging a tourist tax. They also forbid you to sit on steps/shop fronts - forget where exactly, but just be careful - (and Rome has similar) as they can and will issue fines of many Euros! Venice is also very expensive, especially if wanting to sit with a coffee in the main square.
I loved Sorrento and would wander from one liquor shop to another, trying samples of the local drink Limoncello. If they ask if you've tried it before, just say no and declare 'oh, that's delicious!' But don't bother buying a bottle when it's probably so readily available in your home stores, like here. And it doesn't taste the same, either.
I agree about the peace and tranquility of sitting beside a Lake. I've been to both Garda and Maggiore.
Also vehemently agree about watching for pick pockets but that can apply to many countries. Just be careful, watchful and vigilant, and all the rest.
Croatia is also a lovely country. Mum and I did a cruise stop off at Dubrovnik, and after wandering about the town (no we weren't fit enough to climb the walls) we went on a coach trip to a nearby place that was by the sea (think it was Cavtat) and the views on the way along the coastline were just amazing.
Hope you have an amazing time, when you go. Bet you can't wait.