We opted for Captain Kidd's, which has an all-you-can-eat buffet for $10 (drinks not included). The review I just linked to there is almost exactly our experience. A bunch of overcooked food presented badly, but it's cheap. Lisa had some of the seafood stew and said it was okay. I went back to get some, and came back with something else. She said, "No, no, that's Glop #5! I had Glop #7!" By the end of the meal, we were talking about everything on the buffet table as "Glop."
Oh, it's cheap, and it's fast, and it will fill you up. But I won't recommend it as a fine dining experience.
Incidentally, I remember an Indian restaurant that was near the Hilton-Marriott at L.A.con III but was razed some time later to build another hotel. I think it's possible that the same restaurant, or at least one with the same signs and offers (including "American Breakfast every morning") is locate down at the corner of Harbor and Katella, which is around out the back of the Hilton. (Exit the Hilton's front door, turn left, walk down to corner, turn left, walk to traffic light; it's on the opposite corner next to a strip mall of other small restaurants.) They have "buffet lunch every day" in the window, and so I bet I end up eating there at least once during Worldcon.