Hopped around the Parkplace properties during COMDEX (Hilton, Flamingo, Ballys) and got automatic credit for all of my stays within 3-5 days...
Please note that I checked into the Flamingo and Ballys at their "regular" front desks - and both reps were glad to put in my HHonors number.

I certainly hope NJDavid's experience is to be the policy for this year...