Happy Anniversary!
Italy is a great place to celebrate but you only have 12 nights and are stretching yourselves too thin.
Piano! Piano!
A 2 night stay means only 1.5 days at best actually IN your location. You will be spending a good amount of time in transit- (train from Florence to Salerno is 4 hours, then your only transportation option from there to Maiori is the bus- 1 hour--ferries will not be running- so by the time you actually get to Maiori more than half a day is gone. Allow time to check out/check in, get to train, bus, get oriented, etc).
Or hire a private driver.
Another option would be to stay in Sorrento- not technically on Amalfi coast but more will be open in March and you have better transportation options from there.
I agree with all above- cut out 1 location- to me that would be Amalfi just because it is a pain to get to, transportation options will be limited and not really sure how much will actually be open in March or what the weather will be like. Could be cold and dreary. Save Amalfi trip for your 40th anniversary ;)
Rome, Venice and Florence all deserve more time than you are giving them.
If you can change your flights- fly INTO Venice, out of Rome. If you cannot change then head to Venice on arrival- you'll be jet lagged anyway. Eliminates 1 hotel change and gives you a better stay in Rome when days there are all together.
Venice 3-4 nights- depends on what time you arrive in Rome and can get to Venice. Venice needs 3 nights minimum.
Florence- 2-3 nights- easy train from Venice.
Tuscany town Siena? 2 nights- take bus from Florence to Siena as it lets you off in town rather than train which is outside of town.
Rome- 4 nights.
I always recommend Hotel Ala in Venice. Great location with very easy access- no bridges or canals to cross, steps from a vaporetto stop. Good bkft, friendly helpful staff and a pretty nice rooftop deck.
https://www.hotelala.it
Rome- stay in the historic center- near Pantheon, Campo DeFiori or Piazza Navonna- you can walk everywhere from there.