Back to the CCH discussion. If they are looking for a shovel or nearly shovel ready site these are the only locations that I can think of.
Japan Town parking lot, with a potential skybridge connecting to the expo hall.
Dead Goat. A skybridge spanning W. Temple would be enourmous, particularly since I don't see them going straight across (red) considering that would put the skybridge right smack into the Grand Ballroom, so they would have to go on a diagonal. Plus that parcel doesn't seem to have much room for convention space, unless they built all the meeting halls 4-5 floors.
South Temple: I don't see the NE corner of 200 W and S. Temple working as the skybridge would go directly into an entrance, and I would anticipate a tremendous amount of interior remodeling in order to get it to connect to the areas beyond the lobby. The NE Corner of 300 W and S. Temple would have a much easier time connecting to the convention center.
Someone asked about the Radisson Parking lot and the Fidelity Building. As can be seen in this image the parking lot is pretty small, even with the corner Fidelity property and I don't see how they could add a whole lot of additional convention space, unless of course they were to put it on 4-5 floors.
If it is going to be on a shovel or nearly shovel ready parcel, of the four options above I think the Japan Town Parking lot provides the best possible connection, has a decent amount of area available for convention space, and even some large Expo Halls, and a skybridge wouldn't disturb any view corridors. My second option of the four above would the the S. Temple block between 200 and 300 W, using the south side of that block. That location has the most potential for large expanses of convention space, but would require a skybridge for a direct connection and would disturb a view corridor to the UP Depot.
Dead Goat just seems to small with a difficult connection, and S. Temple NE corner of 200 W seems to just have horrible connection options, plus disturbing a view corridor.