Despite being a big, soulless mall peppered with gross chain restaurants you shouldn't set foot in, Kad Suan Kaew's basement has a decent selection of real Thai food at normal street prices. The big, sterile blue area (named "Food Factory," as though that's remotely appetizing) has good duck soup and all the regular items you'd expect, along with draft beer. Around the corner there's an area with curry and khao soy stalls. The selection isn't anywhere near as huge as Airport Plaza's food market, but the food is well done and worth a try if you're there anway.