Convenience: a venue may be super unique and awesome, but convenience is going to be one of the biggest factors in event attendance. Begin by choosing your city carefully (is it easy to get to for your target audience?) and then choose a venue that’s conveniently located near restaurants, coffee shops, hotels, etc.
Climate: don’t underestimate the power of bad weather on your event. Climate is a key factor to think about, especially if any part of your event will take place outside (even if it’s just the check-in line!). And be prepared with umbrellas and reliable AC for unpredictable weather changes.
Cool Factor: throw an event any old city, and you might have a tough time luring out-of-town guests. But throw an event in, say, Sonoma and you just might get people thinking “Well, I’ve been wanting to plan a vacation and I’ve never been to wine country, and work will pay for the flight…”