Honeymoon Help! Greece and where else? Where do I even start!

My fiancé and I are getting married next September and planning to take our honeymoon right after the wedding. We know we want to go to Greece, (a day or two in Athens and island hopping) but have 3/3.5 weeks of vacation and are thinking maybe it makes sense to visit the Amalfi coast. We are first time travellers and are so lost at where to start. Where would you recommend? Any recommendations of where to stay or suggested itineraries? What makes the most sense? How much time in each place? Thank you in advance!