Lela's (tel. 27210/73-5411) has been the place to eat in Kardamili for a long time, indeed. The location by the sea is lovely and the food is fresh, tasty, and -- in that highest of all Greek praises -- spitiko (like good home cooking). When Lela's is closed, there's usually a sign posted with directions to another family-run place.
I've eaten at most of the seafood restaurants on the harbor in Githio, and find them pretty similar. You should get good, fresh fish at any one of these places, so you may want to make your choice based on other factors, such as atmosphere or noise level. If, like me, you like octopus, head for Nautilia (there are usually octopus strung up outside the restaurant). O Potis across from the islet of Marathonisi, has consistently good seafood. Just off the harborfront, by the traffic roundabout, are several ouzeries. Korali serves snacks and light meals at lower prices than the seafood places.
If you are in a hurry, you could try one of the three interchangeable restaurants on Areopoli's main square, which all serve basic meals featuring grilled meats and salads. Lunch or dinner at any one of these costs from about 12€.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.