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That's an excellent question. It's been about 5 years since I went to the CO renfaire. I thought it was a very nice faire. Very comparable to several of the east coast faires, I think, such as Sterling in NY, and the Pennsylvania faire. Both of those are similar in size and permanent structures, though the PA one is a little more artificial.
My favorite would have to be the Maryland faire currently, as it's one of the largest and most robust of the east coast faires (not to mention it's my closest one). It has a fantastic atmosphere, and about 2/3 of the site has tree-shade, which is a huge plus. The biggest problem I have with it though, is that they haven't allowed swords for a very long time. Most faires will allow them as part of your garb as long as they are "peace tied" so that they can not be drawn. But MDRF is owned by a family of lawyers who just don't want any liability risks, and there were a few isolated incidents of patron stupidity many years ago. However, they still have 4 or 5 sword vendors.
So far I haven't found any that I thought were a complete bust, except for New Jersey. That one may have grown by now, as the last time I went there was in 2000. But at the time it was extremely small, having only about a half-dozen vendors, and the small cast was split between a couple of stage shows and street acts (with quick costume changes), and some of the merchants were rude to us.