As long as you want! Just make sure you catch the last elevator down :)
There's no time limit on the observation decks, but the average length of stay is about 45 minutes or so.
No time limit
There's no time limit to my knowledge and they close at midnight!
No limit
No restriction on time, you can be there up to last elevator going down
As long as you would like to. Trips down the elevator happen on a constant cycle
Self guided when i visited so wasnt restrictions on when to depart. Id assume when busy might be different length restrictions.
Thanks! Your answer is awaiting moderation.