Villefrance,France - Visit that town, get a 1 day bus pass, hop on the local bus to Nice, and as far as Monte Carlo.
Kusadasi(Ephesus), Turkey- Depending on time, vist Ephesus. Possible to to on your own via public mini buses.
Santorini, Greece- ride up the hill on the cable car, or take the donkeys. Possible to walk too, takes about 45 mins. Hop on the local bus in Fira and go to Oia. A must see town.
Naples,Capri, Italy- 3 options. 1) visit Naples 2) take the local train to Sorrento, maybe even hop on the Sita bus for the trip along the Amalfi coast. Vist Positano and or Amalfi 3) In Naples, get on a hydrofoil to Capri for the day.