Discovery is headed to the Smithsonian, but Atlantis and Endeavour will be up for grabs. Florida and Texas claim priority, but 21 museums nationwide all want one. They've racked up a lot of mileage, and their $28.8-million price — sans engine — should be enough to cause sticker shock. But that isn't stopping institutions from Los Angeles to New York from engaging in a new space race to land one of the soon-to-be-retired shuttles.