I have a building that is roughly 25k sq. feet. I do rent so I have some offices rented and have to take them into consideration when building a new server room - noise, server hum, heat, etc. The electrical panel is right inside the side entrance conveniently located by a 20x20 room that would make an excellent server room, it has an outside wall and it is away from any renters. There is even a huge ugly green power thing on the outside of that office that would make hiding a few window air conditioners really easy.
Unfortunately that puts me at the far end of the building and I will be over the Cat5 limit and won't be able to reach the outer offices (there are about 24 offices just in this middle part of the building). Also, on the north side of this office there are about 30 more offices (8500sq ft) that will also need to be cabled...