Recent discussion on St. Regis here:

http://www.flyertalk.com/forum/luxur...ce-venice.html

Since it's an anniversary and Rome is not that great when it comes to "Wow" type of hotels, why not spend one night there and then hop into eurostar and be in Naples in 1.5 hrs and then another hour by car and you're on Amalfi Coast where you could celebrate in a more unforgettable fashion? You could most likely even still swim during first week of October.