I am not that opposed to getting them in the AstroDome. A stadium is not a terrible place to house people temporarily, if it is fully functioning.
i think the key here is to just get the folks out of NO. I'm assuming that a vast number of them have friends or relatives in other, safer locales whom they can shack up with for a while, so won't all have to be taken to the Astrodome.
It has to be made clear to them that they will not be going back to their homes for weeks, if at all, so they need to start making plans to stay somewhere for that period of time and not in the Astrodome.
Then find out where they want to go and give them bus or train fare to get there. If that were done in earnest (and I expect it will be), then there should not be that large a number of people who have to be accomodated at the Astrodome or anywhere else.
25,000 will be transported to Astrodome - just reported also on CNN