Our favorite is also Caribe deck on the Grand class. The balconies are half covered. If you are standing by the rail people can look down and see you.
If I recall correctly the railings on the balconies have Plexiglass with a wooden top.
There were two small plastic chairs and a small table on our balcony.
I'm not sure what you're asking about the aft balcony? If you can tell us the name of the ship and the deck, I'm sure someone will be able to answer you!
Have a great cruise!