Thanks all, very interesting approaches!

Here's a twist to it.

The credit I have is $700 leftover from a personal use.

I have a flight coming up with work - the policy is to fly cheapest fare.

Anyone know if there is a way to purchase the fare (tango class tickets) - that amount shows up on my company credit card as $500 for example.
After this- call in, and apply my $700 credit to up the fare to latitude or Flex, without affecting how it shows up on my company credit card?

My company has this horribly inflexible concept for this, despite the fact that 0 sum loss to the company, if it doesn't match how the expense program is designed, we get in all sorts of .......

Thanks in advance!