Technically speaking, US only allows a bonus of 50K per calendar year. But, I think all of these different promos have messed with their systems. So, I would venture to say that you should not be worried even if you took advantage of their last purchasing offer (as I did). Also, if you are looking for several biz. tickets, the best thing to do is to get the login info of friends/family and have them "buy" you miles. Just use YOUR credit card when purchasing time comes... Works like a charm. I'm flying biz. on the following itinerary thanks to their last offer:
PHL-LAX-BKK
BKK-ZRH-LIS
LIS-FCO-PHL
THANKS US!