4 days free in Italy

Yeh, Venice for sure.

I think spending the time in Venice would be my top priority, but I'd check the weather a day or so ahead to be sure it would be OK (whatever that means to you) for wandering outdoors.

If you're comfortable driving the rural roads in a manual-transmission car, you've got lots of great little hill towns to explore. You could stop in a bunch of them. You wouldn't be limited to just the most touristy ones that are reachable by bus.

Lucca's 80 - 120 minutes away. Nice walled city. Worth an overnight.

I usually suggest Orvieto for people day-tripping from Rome, but it's only about 2 hours from Florence. Very nice. On a hill. Worth an overnight. Great cathedral and one or two museums possibly of interest. It would probably take 3 days to see all the sights covered by the city card.

Ravenna is known for the medieval mosaics in its churches but is also a very pretty small city that's great for wandering. It's a bit over two hours (at least) from Florence and requires at least one transfer. It would be pleasant for overnight, but I think it could be done in a day if you got an early start.

If the weather doesn't cooperate, I'd consider Bologna. Large city with an impressive medieval district. Lots of arcades, so you can wander around looking at the architecture without getting wet except when you cross the street. It's also considered a great foodie destination. Museums if you want them.

Lots of folks have favorites in this area. I'm sure you'll get some great suggestions.

Going to Venice is even better idea of you can arrange your flight home from Venice. Why spend time and money back tracking to Rome? Second, I would stay in Rome the night before your departure just to be on the safe side.

So is it reasonable to go to Venice on Wednesday, spend Wednesday, Thursday and part of Friday there then train to Rome where I have to end up?

Would 2 days in Venice be the priority?

Venice is fabulous, and if you have not been there before, should, IMO, be a priority. Go up there Wednesday, stay until Saturday, when you should go to Rome for one night before your flight. That gives you two+ days in Venice, which is a good start. We are about fo make our 8th trip to Venice we find it so enchanting, so you can find plenty to interest you and will no doubt want to return. Should the unthinkable happen and you find you are not mesmerized by Venice, you can always pop over to Padova for a few hours, or even stop there on your way to Rome on Saturday.

Pompeii is harder...a long way and two trains, but you could go to Sorrento for three nights and make Pompeii one of your day trips from there.

Do you recommend day passes for Multi-Day Tourist Travel Cards (boats and buses) or does it make more sense to walk?

With 4 days (Wednesday-Saturday?) you could do Pompeii, Naples, Sorrento and the maybe Amalfi Coast. I may be partial as my family has it's roots in Campania but for me this is the best part of Italy and it is sadly often overlooked in favor of Florence and Venice.

I won't lie, Naples is chaotic compared to Florence, the rest of Europe and the US. Rome would be the closest to Naples I've visited in Italy and it's fairly orderly by comparison. If anything I'd say Naples feels the most to me like South American metropolises like Lima and Buenos Aires. It's a swarming hive of humanity and noise but it's also warm, beautiful, Mediterranean and fits my Italian-American image of what Italy is supposed to be like better than anywhere else on earth. Sorrento is nearby (you can take the Naples metro there) and is much more picturesque and quiet, perched over the bay. It's touristy but in a charming way and makes a great base in the area, especially if you're interested in seeing the Amalfi Coast. Naples and Pompei are easily accessed from Sorrento via metro and/or ferry. Other great trips in the area include Vesuvius, the Greek ruins at Paestum and Capri. Oh and there's the pizza, sfogliatella, mozzarella, basil, best seafood I've had in my life, coffee, etc. Plus the train ride from Naples to Rome for your flight home is a lot quicker than Venice to Rome would be.

Do you recommend day passes for Multi-Day Tourist Travel Cards (boats and buses) or does it make more sense to walk?

We like to get vaporetto passes. Then we can jump on just because we feel like it. You must take a vaporetto to go to Murano, Burano, Torcello, San Giorgio Maggiore, and it is nice to take a cruise down the Grand Canal. At €7.50 per ride, you amortize a pass quickly, and it is convenient. We at minimum break even in a 3-day stay.

IAWL (I agree with Laurel). The vaporetto pass pays for itself quickly if you visit the islands or want to cruise the canals. Plus, at some vaporetto stops, if you make a mistake by going to the wrong loading area, you have to exit and pay to enter the correct one. That turns one ride into a €15 trip.

Based on your suggestions and because I may never get to go back, I have decided to spend Wednesday and Thursday in Venice and travel Friday to Rome which should give me one and a half days there. I did have some things I wanted to do in Rome. One was the catacombs, the Trevi fountain was closed last time as was the Mamertime prison for repairs. I did the Vatican museums but not St. Peters so I think I have plenty to do in Rome on my checklist.

Now I need to plan two days in Venice...