When this shit happens, I'm going to work: Up on the side of a mountain. It's cold. Massive number of buildings and generators. Lots of concrete, security doors, and raised walk ways. Lots of windows for visibility. Low population area. A few narrow gaps between buildings that can easily be tightened up for security.
Roofs are easy to get on to. High buildings. Phone tower on the top of the library (handy while the phones still work). Library also still contains books which will come in handy for fires when it gets cold. Mass cooking facilities. Nurse training facilities, so mini hospital on site (might need some drugs though). Trucks and all sorts of handy plant equipment. When the power finally goes, we can start using the bazillion computers for inflicting blunt forced trauma to the undead. It's like a good sized country town condensed to one patch of dirt. The only thing we don't have is an armoury.
I'll supply the building access card if someone brings the firepower :p
I'm from the Internetz. I've got this shit sorted. :D