I like to go to the Killiney area for food as it is within town, yet slightly off-the-track. Most of the restaurants there are usually not very crowded; you can easily walk in and get a table without making any reservation.
However, if you are thinking of going to Suanthai Restaurant after reading this review, make sure you call to reserve a table – the $19.9++ Thai Buffet is one of the most popular options in town, and they are always packed during mealtimes.