I had actually wished for this in the past. The 7 night certificate breaks into a 5 night and 2 night certificate at some point (I don't remember if I applied it to a reservation and cancelled it or if it was when I got it extended or something else). I had a 5 night reservation on a hotel that was going up a category and decided to use the certificate for that. A flight was cancelled and we had to stay an extra day, but of course it was now a category 7 instead of 6. I wished they could just increase the 2 nights for 10K points, and I would use that towards the reservation. But that didn't happen.