Here are the playsets I would love to see:
Death Star - I would go for an 'all-purpose' Death Star that would allow it to be used as either Death Star. It would have a Throne Room, a Hangar, a Detention Block, Garbage Compactor, and the chasm to swing across.
Echo Base - It would have a Hangar with Tauntaun stable area, a Medbay with Bacta Tank (with exclusive Luke in undies), a big blast door, a turret and one of those tille radar dish looking things. It would also incluse a snowspeeder.
Cloud City - It would have Carbon Freeze Chamber, the Gantry, 2 hallways for battles, and the dining room. It would also include an exclusive Lobot figure, and a Twin Pod Cloud Car.
Jabba's Palace/Pit of Carkoon - It would have a cute Sarlaac, 2 skiffs, and a Jabba's Sail Barge backdrop. Turn it around and it would be Jabba's Throne Room with a trapdoor with a cute rancor underneath. It would also include a cute Luke with a bone figure.