Naples and Amalfi Coast

Who is “we”?
How many travelers?
If there are 3 of you one suitcase each would not be difficult

Two of us.

You didn't specifically say you are sleeping in Sorrento too. Is that the case?

The Naples train station is quite modern. It has an escalator to all levels, although the Circumvesuviana tracks are a long (level) walk on the lower level. Smooth marble tiles. The Sorrento Circumvesuviana station does have a modern elevator, which posters on this board have used. I happen not to have used it. Note that Sorrento is not, technically, on the Amalfi Coast. It's on the Gulf of Naples. Sorrento has some cobblestone streets. I can't imagine a taxi in Sorrento under 15 Euros. If you are using an especially cheap hotel, it's likely to be some distance from the train station.

The Pompeii Circumvesuviana station is on the same level (maybe a couple of steps) as the street, which you simply cross to get to Pompeii. I admit that I don't remember how you cross the tracks there is that happens to be needed. (I mean grade level, or stairs.)

There is a private bus company that goes from the airport to Sorrento, but I haven't used it. The issue with the Circumvesuviana isn't stairs, it's crowding and absence of long-distance luggage racks. However, legions of budget travelers continue to use it for the cheapest, reasonably reliable, ride from Naples to Pompeii or Sorrento.

We don't have many reports here on crowding in September. Please post again after you make this trip, to help later travelers.