Crowne Plaza at Union Station is a really nice venue. Not cheap but historic and they do up receptions there with flair. I have been to a couple of weddings there the past few years and have been impressed.
bmrey007: Check out Scottish Rite Cathedral, the Murat, and the Indiana Roof Ballroom. The Murat is the least expensive, Scottish Rite is in the middle, and the Indiana Roof Ballroom is at the higher end. I have ceremony and reception venues staked-out (including the Rathskeller), but unfortunately none of it matters until I make the deposit to save the date... Good luck finding a venue!