Extra day in Rome or Capri?

I would not cut time in Rome, you can't see it leisurely even in 3 days. You can trade-off Positano for Capri if you really want to see Capri. It's larger and a good spot for hiking.

Our day between these two areas, we want to go from Sorrento, stop at
Pompeii and possibly do some hiking on Vesuvius, then head to Rome by
train. Can we do that and get into Rome not too late at night?

That will be one one tiring day. There's no safety issue about getting into Rome late, the only downside is that you'll be really tired (and probably the next day too).

How long is your whole trip? No time in Naples?

Do not cut time from Rome. You have so little time there as it is.

How long is your whole trip? And where else are you going? Where are you coming from?

Presumably/hopefully your trip is more than 5 days...?

If all you have is 5 days, there is no 'extra' day

I agree with the other comments-- do not cut from Rome. And I expect your overall trip is longer than this. It would help to know where else you are traveling.

You need more time in Rome

Thank you for your replies! Yes, our whole trip is 12 days. We get in to Naples, plan to do Amalfi coast area, head up to Rome, then to Florence, Cinque Terre, and over to Venice...a couple days in each place. Home from Venice. I know it’s a lot of travel but we can’t stay longer (young children at home) and we want to see as much as we can.

You definitely need more than 2 days in Rome. Visitors who often say they disliked the city did so because they didn't give enough TIME. Personally, I consider 4 nights/3.5 FULL days the minimum for Rome, and we have almost 2 weeks under our belts over a couple to trips and have yet to run out of things to do.

We want to see main Roman sites, but can we enjoy it in 2 days?

As above, you need 3 FULL days in Rome to do it any sort of justice.

We have 2 days in Sorrento (one to relax after a long flight, one to
visit Positano and do some hiking),

Is that two FULL days or closer to 1.5 days with transfer from an airport? Naples, Amalfi coast, Rome, Florence, Cinque Terre, and Venice is WAY too much for 12 days, IMHO. I'd skip the coast entirely as it's the outlier.

I know it’s a lot of travel

Your trip will be just that, a lot of travel

Since you cannot add time, you should trim your destinations.

If you choose to keep Venice in the mix, suggest you start there. If home is N America, the cheapest flights from Venice are at o'dark ugly and make for getting to the airport expensive or inconvenient or both.

When you start plotting out all your transfers, checking train schedules, etc., you will see how impractical it is to try to see so many places in your time frame.

I am also someone who love to see as much as I can on vacations, but I really think yours is too aggressive. Too much traveling. You don’t need to see the Amalfi Coast and Cinque Terre both on one trip.

Decide whether Florence or Venice is pulling you most.

Sounds like you want to start in Sorrento.

Sorrento/Positano/Capri/Pompeii.....4 nights. (These are nice day Tripp’s or even 1/2 day trips)
Rome......4 nights
Florence .....4 nights (with a day trip to small town)

Or

Sorrento....3 nights
Rome.....4 nights
Florence 3 nights
Venice 2 nights (if you must)

Do not do any less than 4 nights in Rome, you’ll regret it.

Thank you all for the advice. You’ve definitely convinced me to not cut time in Rome and that we probably need to rethink visiting ALL of the destinations on our wish list in our short time. I’m probably least excited about Florence, but understand I don’t need Amalfi and Cinque Terre. I want to be able to enjoy the trip without feeling like I’m constantly traveling. Thanks!

If you decide to cut Sorrento and keep the Cinque Terra, use this path.

Venice 3 - Florence 3. - Cinque Terre 2. - Rome 4.

A way to look at this is too look at RS tours of these areas since you are on his site. You can get a good feel for what you might be able to see in a day. Now remember on his tours you will see a lot more than on your own and transportation is included.

Do not under estimate time to travel. Packing up & moving you lose at least half a day each time you move.

Where are you flying from and to? Direct to Naples? Jet lag can cost a day too. We recently were in Sorrento for two nights which was really only one day with travel. I wish we had that third day there. Enjoy