Should I purchase tickets for major sites - Colosseum, Uffizi, Vaparetto Passes, etc. before we leave for out trip? Is it more cost effective? What about purchasing the Roma Pass? and Venice Connected? Are they worth the expense? Again, purchase at home or in Italy? Thank you for your help!
For places that require a timed reservation, you might want to purchase ahead of time (Leonardo's Last Supper, Scrovegni Chapel, Galleria Borghese). Skip-the-line passes can be purchased when you get there, also the vaporetto pass.
To the list in the preceding message, definitely add the Uffizi and Academia. They can be hard to reserve if you wait until you are in Florence.
Agreed; you reserve the sites that require or strongly recommend reservations, but there's no need to buy passes or some recommended combo tickets (Colosseum, Doge's Palace) ahead if you follow Rick's tips in the book about where to buy them.