4 Days between Varenna & Venice

It depends on what you enjoy doing.

It does depend on your likings, but I would say part of a day and maybe an overnight night in Verona is plenty, I'd spend the rest in Venice because I consider it the most beautiful city I've ever been to (so far, I'm not done yet). You don't say how you are traveling (car? train? bus?), but with travel time between Varenna and Venice, you're eating up a good chunk of time just in travel. I'd narrow down your choices.

Thank you - yes, I was rather vague, wasn't I? Here is our itinerary so far: Flying into Milan - staying overnight Morning train to Varenna, then bus to very small village 20 minutes from Como where we are doing a language program for one week. We will have spare time to see Varenna, Bellagio, and hopefully some of the other towns on Lake Como during that week. From there it is open until the last three days of the trip which we will spend in Venice. I have been to Venice before so I think that will be enough. We are not big art or history buffs - would rather just admire churches, castles, museums from the outside and spend our time walking around, exploring little alleys, restaurants, bars, and people- watching. We want to feel Italian life, not stand in line with tourists. We will have a rental car in the lake district but are thinking train for the rest?
Then train from Venice back to Milan for flight home.

We spent 2 nights in Verona and saw quite a bit in our full day and partial day. We could have found more things to do if we had more time. We arrived there from Varenna and went on to Venice from there. If you are traveling by train you might want to consider staying in Verona the entire extra time you have and use it as a base. Lake Garda is nearby and accessible via public transportation.

Have you considered flying home from Venice (Venice Marco Polo airport) since you are ending your trip there? You might consider visiting Mantova or Ferrara if you have time, but it looks like your itinerary is already full.

Scrovengi Chapel in Padova - a must see. Didn't much care for the rest of Padova. Have a look in the RS guidebook for many ideas...

If you decide to do the Scrovegni Chapel, you have to make reservations well ahead. They do the same thing as the Last Supper - allow small groups in for 15 minutes at a time, then out you go.