I just had my first Marriott stay post-SPG/MR combo (which didn't go smoothly for me - several do-overs on SPG/Marriott side) and the points posted as follows:
+2,000 Points
(1,000 Base + 0 Elite + 1,000 Extra)
when it should have posted for about 8,500 points. I called and was told that I had elected to credit miles to US Air. Two issues. First, I have not credited either my Starwood or Marriott stays to an airline in the last five years (if ever?!). And, second, US Air doesn't even exist anymore. So, I looked at my new "merged" account and sure enough - it appears that in the combination that my preferences have been set to crediting miles listing my old US Air FF#. Everyone might want to check their preferences.
And here's the best part, I can't be credited for the points until the SPG/Marriott folks figure out where the paltry airline miles actually went...since they can't find any contact for US Air (I did point out that it is now American). The agent let me know that I should call back in three or four days and check on my case.