Platinum will get you the benefits. Gold will get you.... nothing....

You roll in to the garage and get a ticket through the machine, then on the way out there are pay stations which will validate your ticket and take your payment. You use the ticket to open up the barrier and off you go. If you find a diamond card in your travels around the casino then all the better

If you didn't want to pay, you can park at Rio for free and take the shuttle to Ballys/Paris.