Specific to the SPS corals and chalices I feed Oysterfeast 2-3x's per week. The rest of the time they get light, poop, and whatever else they may capture and ingest.
I have read a lot of articles on SPS capture and ingesting of food and a feeding response does not always equal ingesting of the food source. That always made me think of how sad that must be for the corals. They get all excited, respond, then don't really get anything because it is not the "right stuff". I think a lot of the food suggestions in this thread are good ones :D