Based on the idea for the Death Star playset, a redesigned Star Destroyer is a must. It could easily be the size of the Queen's ship and look pretty authentic on the outside...
...and when you remove the exterior panels, you've got maximum playability inside. With a slightly shorter profile than the vintage edition, Vader's meditation chamber could easily be fit in near the back where the tower is. Add in a main bridge area and we're good to go.
The underside "docking area" obviously wouldn't be big enough to fit a 3 3/4" scale vehicle, but then again there aren't any! Instead, Micromachines could slide in to fulfill the need for flight play.
The engines could house blue lights.
There could be a hatch coming from the tower which "releases" garbage and is big enough for the Micromachines Slave I.
Skip the ridiculous big dart firing guns and integrate that technology into the front end or sides of the ship if necessary.
Reactor balls on the towers could be "explodable" to recreate ROTJ fun!
Who wouldn't buy this ship? The only reason I can imagine being hit with is that the Queen's ship didn't sell that well. First off, the movie wasn't as well received as the original trilogy so that might have something to do with it. Secondly, practically everybody alive (allow slight exaggeration) knows what a Star Destroyer is. Reluctant parents on the Queen's ship would probably cave in to Jr's wishes on this one.
C'mon, who's with me?