Just had a stay at MGM Grand last week post to my Hyatt this morning (Sunday).
All resort fees automatically waived - not sure if checking in at the front desk made a difference there. I did online check-out because I didn't want to stand in any lines or waste my time.

When checking in and asking about Hyatt, the receptionist noted that I had actually been set up to receive Southwest points instead of Hyatt and had to correct it for me.