Try one of our beautiful southern mansions. There are several. Riverwood Mansion, Two Rivers Mansion, or Belle Meade Mansion all do lots of out door weddings. All have websites if you do a google search.
I got married last year at the Sheraton - Music City. It doesn't have a gazebo, but they have an outdoor courtyard in the center of the hotel. It was an absolutely beautiful backdrop for the ceremony. We didn't need very much decor because of the beautiful landscape. We had about 200 guests in attendance. I've attached a picture provided by the hotel when we were planning our event last year. Contact April Crysel at the Sheraton - Music City for more details. She was really great to work with.
If you live near Lebanon, there is also Blackhaven Wedding Garden. They have a great website too.
There is a new city park in Murfreesboro, off of Medical Center Blvd across the street from The Avenue. That has a beautiful lake/gazebo. It is so pretty!!!!! And also the Embassy Suite Conv. Center is also next to The Avenue, possible place for a reception....
The Millennium Maxwell House has a pavillion and CJ's off the square is nice.
Click on each tool to see a sample.