i think i already answered this on your old post but in all the callbacks i went to, interviewees were permitted to store their luggage in closets at the reception area. you can store your luggage, laptop, umbrella, whatevers into that closet. for half of my callbacks the recruiting people met me after my last scheduled interview just to give me some more info on their recruiting policy and when i should expect to hear back. at that point they will escort you back to the reception area for you to pick up your stuff.
a few times i was left on my own after my very last interview and i guess you can walk yourself over to the reception area and take your stuff out.
hope that helps