BTW, for Starwood sleepers, all three Buenos Aires hotels are now available for points or C&P, but the rates look pretty low for the weekend, including both Sheratons and the LC. I think the rates might have dropped within the last few days, so if you have a booking that can be cancelled, you might want to check spg.com.

ADDED. The Park Tower is US$151 plus tax/service on a nonrefundable rate while the Sheratons can easily be booked around this rate with a pretty liberal cancellation deadline.