and click on Theme Park Venue Map, you can select Hollywood Studios and see most of the major venues available for special events. Not all of them may be open to Disney's Fairy Tale Weddings, but it will give you an idea of the possibilities.
If you have a special location that you are interested in you should speak to your wedding team at DFTW to see if it is something they can work with you on. A lot of it depends on the theme park management rather than weddings.
We got engaged in front of The Hollywood Brown Derby and I asked about doing a reception there. They said it is possible, but you have to pay the restaurant's minimum and you can't get in there until an hour after park closing. Where at MGM did you have in mind?