3 nights in Venice and 4 Nights in Florence w side trips-which itinerary makes more sense?

Padua is nice - there's the Scrovegni Chapel & museum nearby, the oval Prato della Valle, St. Anthony's Basilica, etc. Padua is 30 minutes from Venice. But, if this is your first time in Italy, you might want to visit Verona, instead. Take the train to this town where you'll find more English-speaking help (pay the extra for the 1 hour train vs. the slower 2.5 hour train). Verona's main sites are: a Roman Arena, Piazza Bra and Piazza Erbe, Lamberti Tower, Romeo & Juliet (Juliet's fictional balcony), shopping area with pink granite street, etc. We've spent 3 days in both Verona & Padua.

Venice:
Day 1 (day of arrival). After check in I would visit the islands of Murano and Burano first thing. More relaxing (since you'll be on a boat for part of the visit) than crowded Venice while still jet lagged. When you are jet lagged you want to stay outdoors, not in museums, because sunlight is necessary to adjust your body to the new time.
In the evening, when you return to Venice and when lots of cruisaders are gone away back to their cruise ship, that's the time to stroll the 'calli' (streets), the 'campi' (piazzas), the canals, and also Piazza San Marco.
Day 2: That's when you can visit some museums, but don't overdo it. You don't need to see every museum and you don't see everything inside each museum. Same is true for churches. Take time to just stroll around, look at the beautiful palaces while walking or from the vaporetto.
Day 3: Day trip to Verona or Padua (both in a day would be really too rushed). You don't need the whole day to see either. Half a day is good to see the major sights of either. When you are back in Venice, enjoy your last evening in Venice.

Florence:
All options are good, depending on your preferences. Whichever option you choose, remember that you don't need to see every museum in Florence (that would be challenging since there are about 60-70 museums in Florence, without counting churches, cathedrals and private palaces). Also you don't need to see everything inside the museums you visit. When you go to a restaurant you don't order every item in the menu, so the same approach applies to museums and art in general.

I personally would not suggest going to the Cinque Terre as a day trip from anywhere. If you had time at the end of your vacation, it's a great place to relax, hike, and just slow down and enjoy yourself after a busy sightseeing agenda. But that doesn't sound like your situation at all. Making your way from Florence to the Cinque Terre is about 3 hours by train each way, with two changes along the way (in Pisa and again in La Spezia). I just think that's too much traveling to get to a place where the main thing to do is take it easy.

I suggest Florence 1.

I wouldn't do the day trip to Cinque Terre, for the reasons given by Lane.

Thank you all for the great information!
Yes, a 3 hour train trip to Cinque Terra does not make any sense at all, but my wife would really like to see the towns and we we should be able to relax when we get to Sorrento later in the week.
I have been looking at some tours of Cinque Terra through Viator and Walkabout Florence. They have great reviews but no one mentions how long the bus ride takes to get there. It would have to shave a lot of time off to make it worthwhile.
Does anyone know how long a tour bus takes to get to Cinque Terra?

If its Autumn/Fall (Oct/Nov) I would definitely leave out Cinque Terre.
The Bologna stop off is a good idea if you have your luggage sorted (left at train station).
Padua is definitely worth a full day ...
Old centre with Duomo, Baptistery, Piazza dei Signori ,Caffe Pedrochhi, Palazzo Bo (university)
Piazza della Frutta and Piazza dell’Erbe on either side of Palazzo della Ragione (law courts)
Basilica di Sant Antonio and the historical botanic gardens (Orto Botanico)
Giotto’s Scrovegni Chapel and the Eremitani Museum

So, my friend wanted to see Cinque Terre, he had spent some childhood time in Monterosso. We (3) were staying outside Sestri Levante. We got as far as Monterosso, got into the lemming promenade, turned around and caught the next train back and spent the day in the mountains. This was June 1. Fall may be much better.

Seriously, Cinque Terre should not be a day trip. I really suggest 2 nights. I went in March and had a blast. Also your second day in Venice is WAY too ambitious and filled with sites. Take time to just wander, especially into the Dorsoduro neighborhood and find a cafe to hang out in!

Your basic plan is fine, 3 nights Venice, 4 nights Florence. And it's good to have a plan, but instead of agonizing over it, I would have 2 plans in hand and then be flexible and make choices on the spot. You really don't know how you're going to feel when you get to Venice - how much the lack of sleep and jetlag will impact not only Day 1 but also Day 2. You may decide on Day 2 that you have seen enough of Venice, then take a day trip to Verona. But you may want to stay and enjoy Venice for one more day. Padua has interesting sights, but I don't think it compares with Venice or even Verona. The main draw in Padua is the Scrovegni Chapel. Consider that you'll only have about 15-20 minutes with the frescoes, but it will take you several hours to do that. If this is a really high priority for your group, you can stop in Padua on the way to Florence, leaving your bags at the station. It's short walk to the church. If you're going in late September or early October, you can probably still reserve tickets a day in advance. You could even spend most of the day in Venice - or Verona. Instead of seeing Bologna, go straight to Florence, which has so many more sights.

Relax and enjoy. It's all good and you'll never see it all anyway. Assume you'll go back, most people do.

The Rialto market is only open in the morning.

bluehenner
I don't know how long it would take from Florence to the Cinque Terre by bus, since I've never taken a bus there. However from my house in Florence (near Viale Europa) to Riomaggiore by car I could make it in just under two hours on a good day. On a summer weekend...forget it!

Thank you all for the information, it was most helpful.

I never even considered jet lag.

I've decided to leave the third day in Venice open so we can stay or do a day trip to Padua, depending upon how we feel.
Will make a stop in either Verona or Bologna the day we tavel to Florence.
Do a tour of Tuscany the day after we arrive in Florence with the remaining time devoted to Florence.
I'm sure Cinque Terra is beautiful but we will save that for another time.

Does anyone have experience withh storing luggage at Verona or Bologna?

If you decide to rethink CT, fall is the perfect time to go... there are far less crowds and you can have some beautiful weather. It makes it so much more enjoyable when you are not sweating and packed in with hordes of tourists. If you want to experience it as it was a number of years ago, then it is better to go off season and take your chances with cooler weather. Otherwise, as Zoe mentioned, it can be grueling.

In your rush to "see everything" you may find you see or remember very little. Make a list of possibilities and be flexible. Seeing something and taking time to enjoy it can be two different experiences. Assume you will return one day.

Roberto, Chani and Richard,

Your advice has been heeded. My itinerary is now just a rough outline, it will be very flexible. The only things that are concrete are my train tickets and and a few of the major museums that I'll need to schedule in advance.

Thank you!

The big stations in Italy are easy for luggage store - and no fussy lockers.
http://www.seat61.com/luggage-lockers-at-stations.htm#Left_luggage_offices_&_lockers_in_Italy

Day one- Venice, check in, Academia/Guggenheim or Ca Rezonnica, Saint Marks Sq, San Giorgio Maggiore.
Day two- Venice, Bell Tower, St Marks Basilica, Doge's Palace, Correr Museum, Ca' d'Oro, Rialto Market, Cichetti Crawl
Day three- Venice, day trip to Padua.
Day four- Florence via Bologna or Verona, late check in, relax in Florence.
Day five- Florence, day trip to Tuscany.
Day six- Florence , Academia, Uffizi, etc.
Day seven- Florence , Academia, Uffizi, etc.