Originally Posted by
drew in the air
...when you hit 1K or higher, you get GPUs which can be applied instead of miles/cash
Well, cash comes into play for a lot of travelers who have to cough up for higher fare class in order to use the GPU. Unlike cash used in a mileage/cash upgrade, the cash differential between the cheapest available and GPU-usable fare classes is not refundable if the upgrade is waitlisted and not cleared.