Please review my plans!
 

I've finally booked flights. We flying into Venice, arriving Sept. 30, and leaving from Rome on October 16th, so 16 nights.

Tentative plans are 2 nights Venice,
3 nights Florence (enough time to do a day trip somewhere?)
5 nights Amalfi Coast
6 nights Rome

I'm wondering if 5 nights Amalfi is too much, and if so, where should I spend the extra night.

We're going to be taking the train everywhere.

Thanks in advance. I'll be asking lots of questions soon about hotels!

Spend another night in Venice--2 nights, including your arrival day, are no where near enough time there.

More time is needed in Venice.

Nice trip, but I would allocate the days like this:
4-3-5-5
It is hard to access the AC so if you do go then stay and enjoy. Have fun !

I can't believe I'm recommending one night less in Rome, but I agree, take that and add it to Venice.

Yes, you can do day trips from Florence if you feel you have enough time to see everything you want to see there. Siena is a lovely town that's an easy 1+hour bus ride to (I'm in the minority that wishes I'd stayed in Siena and day tripped to Florence.) Siena is reachable by train too but the bus is easier; there's no direct train from Florence and it does not take you directly to the Siena city center.

A shorter day trip from Florence - in case you can't fit Siena in - is Fiesole, which is reachable by public bus. Neat little town.

Yes, I'd add a night to Venice particularly because you are ARRIVING there - so with two nights you'd have very little time there.

Five nights at the Amalfi Coast? That sounds a bit much - are you just planning to relax there? To be fair I've not actually been there and the others in this thread probably have - but I wasn't aware it required so much time even to soak it in. Are you planning to go to Capri?

You could stop in Bologna and have a meal, at least, on the way from Venice to Florence; your train may stop there anyway.