Firstly, I think your aim of one to two locations across 8 days is very sensible. Many travellers try to cram too much in (ending up seeing less as they’re constantly packing/unpacking and moving). Late September is also a wonderful time, with the edge taken of the summer heat, yet almost invariably t-shirt weather. I’d rule no location out on a September trip, whereas summer rules out the cities and winter can be difficult in more rural/coastal areas.
Worth looking at flight deals to see what locations have good connections and a good price. This can swing the decision.
For scenic beauty, there are loads of choices, from the Italian lakes, through the stunning mountains, gentle (e.g. Tuscan) rolling hills, or stupendous coastlines, and it is the latter that sparked my 1st thought - Amalfi Coast.
Amalfi Coast accessed via Napoli airport, and 2 hour bus ride, or faster ferry or taxi (about 100 euro one way). Once there, public transport via buses, ferries (and the under-utilised but wonderful trails described in Tippett’s indispensable pocket book in the Sunflower series - also now online I believe). The best views are high up, or from the coast, but if wanting to see Pompeii, Herculaneum, Capri etc. it helps being close to one of the harbour towns. For me Ravello is utterly breathtaking & peaceful, yet by its location, not swamped by tourists. Positano looks stunning approaching from the sea, and mixing that with a bus ride up to Montepertuso and the walk down, gives a strikingly different perspective. Atrani is a hidden gem, cool when everywhere is baking, it’s got something of Matera about it with houses built into the viaduct in a striking maze of pathways. Italian, whilst appreciated, is not expected on the Amalfi coast.
Somewhat more populous, Cinque Terre is often ‘compared and contrasted’ yet bracketed with the Amalfi Coast. More populous, as there is effectively just one long coastal path (with more interesting / challenging paths up and along the hills). The village hopping either by boat, path or train is very easy, and each of the 5 has its own character. The noise of the trains can be initially distracting, but you’ll adapt quickly and provides a point of interest when sitting on a balcony with glass of wine at the end of the day. Logistically either Pisa or Genova airports are easy, and present an optional 1-2 night stay in those cities if you crave another location with a genuine point of difference. Genova is somewhat ‘salty’ yet all the more interesting for not being a significant tourist destination. Pisa is both a huge tourist trap (from either station to the field of miracles), and an under the radar gem (the rest of the city, barely more than a 5 minute walk from the leaning tower/field of miracles. Public transport is basically the only option for Cinque Terre. Again lack of Italian language would never be a problem here, though for some reason most of the walkers assume their fellow walkers are Italian (most are not), so all tend to utter broken 'Buongiorno’s or sometimes ‘Prego’ (you’re welcome) to each other. It makes me smile (not mocking humour) that they are making the effort.
These are just two, but there are limitless opportunities and many brilliant places. These two are very easy for 1st time travellers, with no driving, English spoken widely and both retaining loads of character - affected but not blighted by tourism.
Happy to suggest other options if those don’t appeal. Italy has been a regular destination over the years and it holds some of the most special memories of warm/generous people.
regards
Ian