Actually the glass bottom idea was Angel's my idea was that the Emperor's Palace attaches itself via a pylon like an Air ship and the elevator goes through the pylon into a parade bay (the main hanger in the current version of the film).
Like the Hindenburg docking with the Empire State Building (done rather well in Sky Captain And The World Of Tomorrow):
So instead of stepping off a shuttle he has just popped down a lift to inspect the station and the troops.
When Luke lands he goes up in the lift, through the pylon and into the Throne Room (which could be on the bottom of his Palace ship as much as the top).
It does give anyone wanting to take this approach a free hand to design a new piece of the Star Wars universe.
I quite like the idea of a pyramid but it could be upside down with the throne room on the bottom.
There was an unused Ron Cobb design for the Nostromo in Alien like that (please ignore the bottom picture):
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This looks nice too :
