Kotor, this spring - took a private taxi tour to Perast, and the driver took us to a free boat ride to the Lady of the Rocks and then drove us up into the hills for a view. We arranged with him how long we wanted to stay each place - he was part of a company selling taxi tours at the dock. Very talkative and friendly, taught us lots. Then we walked around inside the walled town for an hour or so, using an online written walking tour I found
Argostoli, this spring -walked around, then took a 5eu trolley tour around the town.
Mykonos, a few years ago, walked in the town, then took a city bus to a beach area, rented a couple chairs and umbrella, took the city bus back.
Athens, a few years ago - took a taxi tour, arranged destinations and times with driver. Driver helpful, talkative, and friendly. Self toured the Acropolis and Parthenon with Rick Steves audio guides we put on our phones. Went to lunch at a Greek restaurant and then went to some other sights and views.