Just checking their website, Union Station rents (a six-hour block) for $11,500 for weddings and other social events. I know that sounds like a lot of money but look at these stunning pictures by Birch Design Studio!
YOu bring up a really good point @noonmarez. LIGHTING. It's gotta be done and done well. A producer friend of mine was asked what is the most important thing for event design. He said, "Lighing is everything." He's right