I discovered an interesting thing about eating in Athens.
Near the big museum was a row of restaurants, and we ate at one restaurant, which actually mentioned RS on the cover of the menu. It claims that their restaurant was endorsed by RS, along with half a dozen other famous tour books. Their whole fish cost 21 euros.
However, we were staying near the Omonia place, and we found a little seafood restaurant, and ate a whole fish meal there for exactly 7 euros. With that difference in price, we were in there every evening. My colleagues say that the 7 eu fish was better than the 21 eu fish. The 7 eu place seemed to be locals only, no other tourists - and very friendly. The owner apparently has lived in New Jersey at times, and when he found we were Americans, he brought out some hard liquor to have a toast. We had a lot of fun at that place.
I guess the moral of the story is - as it often is - avoid tourist areas, and find where the locals eat.
I can provide precise names and address on demand.