Thank you, Susan Blair for recommendations in Crete. Here are some my picks in Athens. Please note it's likely that none of the restaurants listed below has English menu.
Ouzadiko: 25-29 Karneadou Street, Kolonaki. Everything's good here, I think. Melitzanosalata (everyone seems to be tired of this, but you ought to try well-made ones) is one of the best I've had. Rice dishes, maybe except dolmades are made w/ converted rice & are well-cooked (slightly mushy). Flavor is very good, but if you hate converted rice, avoid. House wine is very good. Although there's no dress code, dress smart-casual if you want to blend in.
Marabou: Panormou Street (near Panormou metro station). Simple, but well-prepared good quality food. Bread they serve used to be much better, but they still serve them warm. Seafood (grilled sardines, baby cod w/ skordalia are some of my favorites), hortopitta, country sausage, maidanosalata (parsley dip), kabourmas are good. If you want mussels, fried are better than saganaki. Wine (from barrel) here is very good, too.
Inomagirio: In Patralona (?). I don't remember exact location & is hard to find, but I like the food & atmosphere here. Zucchini & yogurt dip, fried bread, meatballs w/ leeks, slow-baked pork are favorites.
There are some better-than-average restaurants in Halandri area. A place called O tzitzikas ke o mermigas (?) had interesting dishes and, pork w/ caper sauce was quite good. Salad dressing was too sweet. Some of the other dishes are: chicken w/ almond & pomegranate sauce (sweet, but pomegranate seeds were nice touch), mussels in ouzo sauce (it was unavailable when I went).