Seems that Hilton is running a few promos right now for Q2. I usually have my Hilton setting to Points and Points since I love Hilton points and use them more than any other points I have, but I did change to Points/Fixed Miles with Delta to take advantage of the 2013 promotion with Delta. If I max that out I’ll change to United for the rest of the quarter.
Loyalty Traveler gives a good run-down of the different promotions running right now.
Some have reported issues with changing earning styles recently so you may need to tell them at check in (and run the risk of it not going through) or trying on a mobile browser.
I did just check and I did indeed earn the Daily Grand in addition to the Delta promotion on my stays last week.