I don't know if this is what you're looking for but log into your Mileage Plus account then go to "Shop for Flights" and key in your specific destination and dates. Make sure that you are sorting the results by schedule and the inventory for the flights should be available in the results. I tried this method when there were no award tickets available for my specific destination and dates. It seems the key thing is that you have to log in so that the system knows that you are in "Expert" mode.