Our outage from Irene was only about 40 hours, but it was enough to convince my wife that we needed a generator. The previous owner of our home had installed a standby generator, but took it with him when he moved. He did, however, leave the transfer switch meaning that all I need to do is have the electrician move a couple more circuits onto the switch and hook up the new generator.

Our big motivator is the sump pump; mine went about 10 hours unpowered until a neighbor brought his generator over to run it, and it seemed like it ran forever. If our basement had flooded the cost of renovation would have exceed the cost of the generator, and that's not even considering loss of refrigerator/freezer contents. We seldom lose power, but it will only take one or two events to make this investment pay off for us.