Very BIG Room? Music and Home Theatre Challenge

Could anyone please comment on issues that come to mind when setting up audio and home theatre in a big, barn like room?

I have been asked by a friend for some advice on a soon to be renovated "great room" which will be converted from a barn that was attached to their house.

Therefore, the new room will connect with the kitchen and extend to approximately 25' wide by 60' long with 14-15 foot ceilings.

The walls are made of stone and the floor is hardwood.

At the far end of the room, there will be a new chimney and fireplace installed, and the only brief I have so far is that will do lots of entertaining in this room, have a bar, and approximately 3 different seating areas within the room, and would consider a large projection or display device over the new fireplace.

The room is naturally pretty dark, which I hope will help with the video aspect.

As a Magneplanar fan, I would like to recommend 3.6s and all the Maggie surround sound speakers, but I need to learn more about their tastes and preferences.

I do know my friend loves to watch football and tennis, so I am also thinking HDTV in a big screen format.

But any ideas for such a project would be greatly appreciated.