I pulled the trigger and upgraded for the 20,000 points.
Uh oh. Looks like in at least one case the upgrade bonus is considered (note text in red).
AMEX SPG LUXURY CARD: Welcome offer not available to applicants who (i) have or have had The Ritz-Carlton RewardsŪ Credit Card from JP Morgan in the last 30 days, (ii) have acquired The Marriott RewardsŪ Premier Plus Credit Card from Chase, The Marriott RewardsŪ Premier Credit Card from Chase, or The Marriott RewardsŪ Premier Business Credit Card from Chase in the last 90 days, or (iii) received a welcome or upgrade offer for The Marriott RewardsŪ Premier Plus Credit Card from Chase, The Marriott RewardsŪ Premier Credit Card from Chase, or The Marriott RewardsŪ Premier Business Credit Card from Chase in the last 24 months.
Therefore, I'm holding off placing any charges on my upgraded Marriott card since that action is what triggers the bonus. Technically, even though I've upgraded the card, I have not yet received the bonus. This is important, because I may want to apply for the SPG Luxury Card. Still need to research it.
RNE, making this wrinkle known to others considering upgrading their Marriott cards.