How about having the Marriott corporation doing an emailed Census to a representative group of Marriott Rewards (MR) members early this year? You've seen all those (expensive) ads for the US Census on TV and heard them on radio (even if you're not living in the US they're on the Internet as banners on some sites.)
This census of a portion (including all elite and non-elite levels, age groups, occupational status, location of residence, etc.) of the thirty million plus members would do several things, all of which are valuable:
Interesting suggestion. Thinking expansively, inviting selected members to provide feedback and suggestions might be combined with a promotion that raises awareness about Marriott Rewards Insiders.
Assuming an online form that requires validation with a MR# and e-mail address the last page might have a link to Marriott Rewards Insiders along with an incentive offer to receive 250 bonus points.