Don’t even think about spending nine days in the Maldives. You’ll be stuck on a resort and, after snorkelling, diving, boat rides and relaxing, you’ll be twiddling your thumbs. It’s beautiful, but save it for when you’re desperate for a short, de-stressing break.
So, Greece. Peak tourist season here is mid-June to early-September (summer). Early November is not a bad prospect, though you should bear in mind a few things. It will be distinctly colder (day temperatures around 20?C) and possibly rainy—showing off bikini bodies on the beach is not an option. Many hotels shut for the winter but enough should be open and may even offer offseason prices (check on booking.com). As far as I know, the ferries between islands wind up by mid-November—but will be available in early November, certainly on the larger ferry companies such as Blue Star (bluestarferries.gr/en). Both Santorini and Mykonos are now ‘all-year’ destinations—as is Athens, of course. I’d say go for it, if you’re looking for a quiet, beautiful, relaxing time with enough to do by way of day trips of natural/cultural/historical interest. Depending on what pace of travel you’re up for, you could also add Naxos and/or Paros to your itinerary (both islands are located between Mykonos and Santorini).