I like Olympia and Delphi so happy that you will do both. When you go to Delphi be sure to visit Arachova, a small village about 10 minutes away. Arachova has great restaurants, shops and charming hotels.
Olympia was beautiful. There are several museums and I stayed at the Best Western Hotel that had a great tavern and pool. Haven't been to Meteora yet. If you go to Northern Greece, Vergina has a really great museum.

Northern Greece has a special story as I was on a bus coming thru in ,77 and out the window saw a sign Thermoplayae

Being interested in history knew this was the place where 300 Spartans held off Xerxes 20,000 army in 480 BC

Will stand where they stood (altho the topography has changed)
and will well please me