Europe in Sept itinerary (half travel + half relax)

We are looking to do our honeymoon to Europe the 2nd half of September. We were originally thinking we’d do 10 days in Bora Bora but we figured we’d get bored… so we switched gears!

We would like to do half of the trip doing sightseeing and the other half going down to the Greek Islands and just relaxing.

The problem is we’ve both traveled to many of the major European destinations (London, Barcelona, Madrid, Rome, Florence, Cinque Terre, Nice, Edinburgh etc.).

We are interested in Switzerland, but curious if anyone had any other suggestions!