Florence and Sorrento or Sicily

Do you have flights booked?
If so to/from where?

Flights are flexible- booking soon

I would not split eight days with places that far afield as you’d lose so much in travel time. Also late October can be pretty iffy as far as coastal weather, but Tuscany has some marvelous coastline right there if you get lucky with the weather!

For a deep dive into something different I would go to Sicily. I've not been there myself. October and November may be the best time to visit as Summers are so hot. It has several layers of history. Have you seen the Streaming Show "The Leopard"? It was excellent, showing off scenic landscape and beautiful hill villages and mansions. Syracuse is a Modern City but a good place to start. I've been to Rome, Florence, Venice and Capri. Since they are Bucket list places; they service the tourists. Capri is usually a daytrip, the biggest part being the boat ride.

8 days are not enough for both Tuscany and Sicily (or Puglia).
Tuscany and Sorrento is feasible.
Otherwise Puglia only, or Sicily only.

Since you've been to Florence already, maybe you should base yourself in Siena or the province of Siena.
To visit Tuscany (other than Florence) a car is recommended, as many hill towns have limited public transportation options.
If without a car, then Siena is the best option as it's the transportation hub for its province and there are buses to certain towns (although not much on weekends).

Sorrento is a good base for the Gulf of Naples area (Capri, Amalfi Coast, Pompeii).

I'd recommend 4 nights for each (Sorrento and Tuscany). Be aware that you need to spend the last night in the city your flight home departs from. So a total of 9 nights on the ground is probably ideal.

The weather at the end of October/early November is not cold but often rainy, or at least iffy, so most likely not beach weather.

Florence to Sorrento is ≈8 hours. It essential kills one of your 7 actual days in Italy.

Either 86 Florence since you've already been there or choose a coastal place closer to Florence. Just bear in mind that some beach type amenities kinda shut down after October.

You could do 8 days in Sorrento with day trips.

I don't know your flight connections but you could see if Palermo or Catania/east coast works as a base for 8 days.

I have 8 days and would love to split the trip

How many nights is that?

As I see it the best case scenario ( time wise) for your listed choices is a 5 hr trip between Florence and Sorrento. That puts a pretty big hole in one of your days.

If Florence is a 'must', I would fly into Naples and home from Florence, doing the 'coastal' part of your trip first.

My $0.02