With the hot season now seriously making itself felt, airconditioned restaurants make more sense these months than ever. A long running and cheap & cheerful place is Pop-Am restaurant. It's like a restaurant cum ice cream parlor, however the food menu is very extensive and the food is excellent and inexpensive. Almost any dish on the menu is between 40 and 60 baht, the simpler 'over rice' or fried noodle dishes cheaper at around 30 baht.
Service is pretty fast too, and did I mention the place is air-conditioned? 8-) One of the dishes I like here (because I don't see it often elsewhere) is Khao Ob Mor Din: Rice baked in a clay pot with ham, mushrooms, raisins and so on. Also nice: Khao Ob Sapparot: Baked rice with yellow curry powder, pineapple, ham, raisins, peas, etc. These are simple dishes of course, but also 'proper' Thai cuisine they do very well, including Tom Yam with very big prawns and dishes that feature a whole fish. There is some Western (or Western-esque) food on the menu as well, like breakfast, hamburger and french fries. There's an ice cream and fruit shake / milk shake menu as well, but I think the ice-cream options are not quite on the same level as the food. A large part of that is that they use the margarine-like paste that so often passes for whipped cream in these regions.. :-S I guess I'm nitpicking, especially at these prices. :-D
Pop-Am restaurant is on Prapokklao Road, inside the old-city area close to Chang Phuak gate opposite the Shell gas station.