In a perfect world I'd have 3-4 days. I'd like a day to participate in the cooking demonstrations in the festival center or do one of the longer lunches with a chef. Two days (afternoon and evening) spent eating and drinking my way around, skipping some each time but hitting most or all in the end. This way I'm not too full and I enjoy the food. We do this for one day currently and it is all lunch, dinner and usually we're full for breakfast the next morning!
A fourth day for dinner event with a chef would be great too. My problem is that you have to plan so far in advance for room (DVC) and restaurants but the festival guide doesn't come out until August. By then I've picked my dates and hoped they lined up with some good lunch/dinner special events. Last year we were there for three days only, mid week, and missed a Jiko Chef's dinner by one day and a lunch by one day on the other end.
Even so, its fun and just roll with it. We spend alot of time sitting, sharing plates, having drinks, people watching. Its my favorite time at Disney.