Sicily without a car - 14 day itinerary

I've only been there once. But I think the only reason to stay in Catania, is to visit Mt Etna. I'd trim a day or three from Catania and add to Syracusa. And fly out of Palermo - no need to backtrack. Or, if not interested in Mt Etna, fly in and out of Palermo. You can still reach the places on your list from there.

I agree with both suggestions. And in Syracusa, stay in Ortygia, an island (connected by a bridge) that is the historical center of Syracusa. Look for little circulator buses that can take you into Syracusa for the archeological park.

Two nights might be enough for Agrigento. Add the third night (and the final night in Catania) to Palermo.

This will give you a good taste of Sicily.

2 nights is definitely enough for Agrigento. 1 night could even do if you time it right; the upper town is interesting but I think that it can be skipped/seen in passing, the main draw is really the Temple Valley and that is not very large.
And Siracusa and Palermo definitely deserve 1 extra night, each.

One full day, meaning two nights in each Catania and Agrigento, as already mentioned by Stan and balso, is more than enough. Catania’s highlights can be seen in half a day especially since you’re going to visit Agrigento. One can visit the Valley of the Temples in 3-4 hours and there’s nothing significant in the town itself. Seeing the temples lit up at night is pretty. I’d add a day to each Siracusa and Palermo. Then, you could take a half day trip from Palermo to Monreale and maybe from Siracusa to Noto. I can’t speak to trains or busses as we had a rental car.

Depending on how many of the baroque villages you want to see, you mght do better with 4 nights in Siracusa. You definitely will do better with 4 nights (I was happy to have more) in Palermo. It has a lot of sights, then you have the trips to Monreale and Cefalu.

I agree that 4 nights is way too many in Catania. If you must fly both in and out of that airport, it would be much more efficient to put all your Catania nights at the end of the trip. If you don't arrive in Catania too late, I recommend moving on to Siracusa immediately. Just don't count that as a sightseeing-in-Siracusa day. This might call for adding yet another night in that city.

Thank you for your feedback everyone!
Making adjustments to my itinerary based on the feedback.