I have been told that travel packages can be upgraded by adding points. Here's an example: let's say you need some airline miles for an airline award but don't yet need the hotel portion of the travel package. So you take a Cat 5 travel package with 100K airline miles, use the miles, but then "bank" the hotel portion of the travel package in your MR account. Later, however, you might realize that you want to use that banked hotel stay at a category 6 hotel. Marriott reps have told me that you can pay the difference in points between a Cat 5 and a Cat 6 travel package in order to upgrade the hotel stay to the higher category.

My question: let's say you have a Marriott Premier credit card from Chase and have an e-certificate (a 43J) for one night at a Cat 1-5 property. Has anyone tried adding points (such as the points difference between a Cat 5 and a Cat 6 stay) to upgrade the e-certificate to a Category 6? (That would be very tempting, but maybe I'm in dreamland with this idea.)