The entrance to the VGC parking lots is directly across from the entrance into the VGC hotel. So depending on the direction you are coming from, for example, if you were going to take a left turn into VGC you would instead take a right turn into the lot. There are attendants at the lot who can direct your guests into the correct location for VGC parking. If I recall correctly they do want to see a room key. I've only parked there twice - usually skip a rentla and take a shuttle or Uber.