The day before Ike hit, my mom and dad got their new 20KW propane-powered Generac whole house generator hooked up. I suspect there will be lots of Houston-area residents making such a purchase after the experience of being without power for one or two weeks.
The generator cost approximately $4800.00. It automatically comes on whenever the power goes off. The noise is much less annoying than a portable gasoline generator. The 250-gallon propane tank cost about $1200. They paid $1250 for the electrician to hook it up, but I would think that the circumstances which dictate the electrician's fee vary widely from one residence to another. The generator used approximately 100 gallons in four days @ a cost of $2.90/gallon--cheaper than gasoline. Another benefit is that the propane is delivered by truck. There was no need to wait in long lines at the gas station to fill five-gallon cans.
Despite the expense, my mom assures me that, "It was worth it!"