Originally Posted by ft101

Be careful - the cheapest ticket is a Business Special which means no upgrade. You need minimum of Business Saver but that runs the risk of any available upgrades being grabbed by others as these can't be upgraded until check-in opens.

To check in advance, do a dummy booking for First Class Reward flights. If these are available then the upgrade is also available. To check after making a booking, go to Manage a Booking and you should find it there. If only one leg then go the route outlined by NYC1 upthread.

For upgrades to Business it needs to be a Business Saver Reward available but I think First Rewards all come from the Flex Plus bucket so you don't have to beware of seeing the "wrong" availability if checking in advance, but wait until someone confirms that as I'm not 100% sure.