Of course this is an obvious must see! We will have more information on tourist packages for you to make sure you don't miss any important historic landmarks. Tip: Would avoid monasteraki square, especially at night Definitely visit the Acropolis Museum after. It is an archeological museum that houses the artifacts found on the Acropolis and the surrounding slopes.
Located in the heart of the Athens Riviera, there is a number of great restaurants and beach clubs. We recommend you check out this area if you have a couple days in Athens and you want some seaside relaxation. Great to spend the day there. It is about 20-25 minutes away from downtown Athens. Glyfaka is also nice but I recommend Vouliagmeni.
If you have the time, we recommend you take advantage and see a few more islands around Greece! From the port of Sifnos, there are direct ferry routes to many islands in the Cyclades, making it a great starting point for island hopping! I recommend going to Paros, Milos, Santorini, Ios, Naxos or Mykonos after. Feel free to message me if you want more recommendations.