Out of all the restaurants we visited (just returned yesterday), Devito's in downtown Eureka was by far the best food. We ate there for dinner but I believe they are open for lunch as well. One day during the week they are closed. They are family owned and have been in business a long time. Our waiter, Howard, has been working their 25 yrs! The food was excellent (I had grilled trout; my husband had the spaghetti combo). The prices were reasonable and the service and ambiance is excellent. We sat outside on the patio looking at the hillside.
The Mudd Street cafe (also downtown) had a great breakfast and I believe they are open for lunch. The tree house owners where we stayed told us about both Mudd Street and Devitos. It is on their recommended list and the list. They had compiled the list over the years from their own experience and guest's experience.
Places we didn't like were Catfish Cabin (catfish was what you would expect but side dishes were tasteless). The service was quick and attentive.
Hope you enjoy your stay. We had a wonderful time in Eureka Springs.