Santa Margarita Ligure? Lake Como? Dolomites-Ortisei?
The Piemonte is beautiful but you will have been in Tuscany. It is less crowded and less touristy than Tiscany but still wine country.
We adored La Minerva on Capri too but it was a hassel getting on and off the island with the crowds. The ferries were easy but getting up and down from the marina was time consuming with the crowds. Perhaps Amalfi Coast?

<i><font color=#555555>"While I will have 2 nights in Rome, my husband will actually have been there for 5 so I can't convince him to allocate any more nights there (my loss!)."</font></i>

It does take two to tango, and mixing business with pleasure changes the dynamic.

<i><font color=#555555>"We found the back canals and wandering around Venice particularly special, it is a strong contender. And who wouldn't be tempted by the Lakes or Amalfi Coast"</font></i>

There are too many gorgeous places to choose from for late September travel dates. Chances are, to get to any one one of them, you're going to lose a travel day. And then there's the other challenge: finding a convenient exit airport. Venice would be the easiest choice for me. It's easy to get to, and it's easy access to the airport. I would have no problem ending a trip at the Cipriani or the Bauer Palazzo in Venice, and just let myself be pampered. But if there's a particular style of <i>cucina</i> you're seeking, Venice can be a disaster. There's never a problem finding great wines in Venice.