If you don't have a spare room to allocate, another option popular in a remodeling situation is to build a false wall in your home theater room. Get some quotes from your local building contractor or drywall specialist. Equipment access is usually a problem in this situation so slide out racks are a good mounting choice. Make sure you purchase and plan for a mounting system that has room for future equipment additions. There is nothing worse than wanting to add that hot new DVD player or 200 CD Jukebox and finding that you are out of rack space and have to cut a new hole in the wall.
Some homeowners prefer to have everything hidden away.
In addition to these locations you may want to add bathrooms, hallways and outdoor areas. Even if you don't plan on installing equipment at every location right away, make sure the cable is run. It is far more costly and sometimes almost impossible to retrofit cable later.