The First Unitarian Church isn't "big" in the sense that it can hold a lot of people, but it IS "big" in the sense that there are a LOT of shows there, along the lines of at least 4-5 a week. They're generally about 12 bucks, and the venue is all-ages, so it's a very popular venue. I've been to the FUC more times than I can possibly remember. It's a great place to see a show and the bands that come through are often pretty awesome (I've seen Boris there tree times, for example).