Beach & Tour: Portugal vs. Italy

What about Rome and Tuscany? That is a lovely time of year to be in Tuscany lots of good harvest meals, wineries, and you could make your way to a beach, but personally I'd just relax n a hill town.

A friend visited Portugal in September and she loved it because the people were very relaxed and friendly. No stress. She described food and culture in the cities as a great and authentic experience.

I spent some May days in Tuscany and another year a few September days at Western Algarve. I liked both regions especially for the nature and culture experience, not looking for museums or stuff like that. The beaches and bays of Portugal in the Southwest region are beautiful and somehow unique. The Atlantic ocean of Portugal is an intensive physical experience - just standing the strong waves and the flow.

Sorry, but when we go to Europe, spending to fly over, we want to see the sites, not lay on a beach.
We can do that in the USA for a lot less $.

Still, you should be aware that the beaches in Portugal on the Atlantic that time of the year will find the ocean cold.

Greece is wonderful, especially if you take a cruise that includes several Greek Islands. Better than Portugal and warmer.

I would definitely go to Greece. September is a great time to go as the weather is still nice but it's a bit less crowded. So many wonderful beaches to choose from.

Sea lover here:
I would also nix Portugal because I think I would find the Atlantic frigid. And I prefer Mediterranean cuisine, but that's my particular proclivity. But, your proposed itinerary for 8-10 days looks manageable for Portugal and the shorter flight is also going to maximize your time so maybe scope out what kind of beach time you would enjoy there.
For Greece I would want a bit more time, because of the flight time but more so because the sheer number of options is so dizzying.
Anywhere in Italy is tops when it comes to wanting coastal time because the proximity is always so convenient for those who want to chill to chill and those who want to explore to do so easily and independently. I would not necessarily pair Sicily with the mainland in that time frame though--too much time lost in transit.
You should consider Croatia also--mostly rocky beaches but really gorgeous scenery, clear seas.
Last wild card I'll throw out--Mallorca.

If you want to go swimming from the beach, definitely take the Mediterranean over the Atlantic at that time - and even northern Italy can be more rainy and stormy than one might think.
Looking at your preferences: Sicily sounds good, and in Greece: what about Crete or Rhodes? The former is still on my tbd actually while we were on Rhodes recently, but either should offer a couple of nice sites, ruins and museums, and nice beaches even in October.

Another vote for Greece. The sea is beautifully warm into October and the beaches are wonderful. Crete would tick a lot of boxes for you all. The weather is better at that time of year as well. Even Mallorca can be hit and miss by early October and Croatia will be too cold.