For a playset, I would want:
Interchangable plates for the background and swap it around so you can have Decepticon base or a Autobot base interior via a sliding system, beds for voyager class sized figures to lie on for ratchet to work on, computer screens that don't Transform and are scaled for the voyager figures to interact with, have a slot on the back to put some pre printed pictures of characters from the G1 cartoon or make your own, so you could have Megatron talking to himself via the computer for example! When you are finished with it, it can fold away neatly and pretend to be a brief case.
Accessories, aside from the table, and computer, bridge controls that connect via 5 ml ports and be moved around, of course various background plates for different scenes, such as the cave where the Dinobots were built in G1 cartoon, a chair for Optimus to sit in, a TINY BWTM2 Megatron, to recreate the scene where he attempts to alter history by killing Optimus prime! A cardboard picture of the volcano that the Ark crashed into would do for a extentior, for the cons, a tower that has a hatch to open and let the cons fly out of, also be a space bridge enterance for Cybertron, for the Earth Space bridge connection, a pop up form with a sliding part that you use a tab for to open and close the entrance, rocks not included, of course a pod to fit a deluxe bumblebee in! Final accessory, energon cubes as a stack, you know, gotta stock pile those cubes