The Casino Garage and the Hotel Garage are two different buildings. For ease to the hotel, Harrah's recommends parking in the hotel garage and using the skywalk located on the 3rd Floor to get to the hotel building.
Doesn't have to be your plan, but the Bride and Groom will be stopping at Harrah's for a late night bite then continue their party at some bars downtown. Feel free to tag along, or feel free to test your luck at the casino!