Additional comment to add - it appears that Marriott 29ways points do NOT appear to be a qualifying activity to extend your Marriott points. As a reminder, Marriott points expire after 24 months of no activity so keep that in mind.
For reference: AMEX MRs don't expire as long as you have an MR card open. Chase URs don't expire as long as you transfer them to an open card.
Most other programs have some expiration policy - examples of ones I think I know off the top of my head:
- Marriott - 24 months w/out qualifying activity
- Southwest - 24 months w/out qualifying activity
- Hilton - 12 months w/out qualifying activity
- IHG - 12 months w/out qualifying activity
- American - 18 months w/out qualifying activity
- Delta - NO EXPIRATION to my knowledge...hey that's one good thing about skypesos!
ADDITIONAL REMINDER: If you're starting to accrue large points balances - consider a spreadsheet to keep track of how many points you have and when they expire. This can also be good to check from time to time to make sure nobody has fraudulently used your points.