We went to the Renaissance Festival on opening day. Had a lot of fun. I was worried about allergies (alternaria mold seems to cause asthma flares that require prednisone), also worried about the level of dust in general, also worried about whether there would be safe food available. Okay, so why did we go? i guess I was just that desperate to do something "normal". My son has pnut and some tnut allergies and we explained that this was a high allergen environment and that we would have to be careful and leave if there was any sign of allergies beginning. We also discussed for days beforehand so he would increase his allergy/asthma meds before and on the day of the visit. We did make a big deal out of it, but the place is so dusty and it's during the time of year when his allergies are just starting to act up.
Anyway, no reactions whatsoever and now he has a strategy for preparing for a high allergen environment - lots of rest and lots of meds (except albuterol) before the visit.
With respect to the food - the people at the booths were hit or miss with their knowlege of food allergy and avoiding cross contamination. Mostly it was miss. We didn't like the booths that were really close to the entrance. We ate popovers and turkey legs at the booths that were further into the festival, we ate cheese curds, beef stix, and drank soda and water. I brought some food along although the website said no outside food allowed (our backup plan was to leave it in the cooler in the car and go out and eat it if we needed to).
We fenced, shot arrows with a recurve bow, played chess with a giant chess set, played chess with a normal chess set against the chess master, watched jousting, sheepherding, acrobats, comedians, wandered into shops and didn't buy anything, listened to riddles, had a wonderful time. It was a great day and I could get really used to going places and eating fair food without having any reactions!