It's a genuinely interesting design but it does make the throne room (unless I'm reading this wrong) still part of the Death Star and not part of the palace, which makes the palace idea somewhat redundant.

I'm beginning to see the virtue in seeing the palace lift off (something I previously didn't think at all necessary) because it creates a look who's coming to dinner feeling so when the palace ship arrives with all the pomp it makes a big event of the thing.

The lift off needn't be a long sequence, no more than a minute maybe even less, it could even replace Vader's walking away from Jerjerrod which never really impressed me cinematically. The last blast of the Imperial March could be taken up with the Palace rising out of the city scape and jumping into hyperspace.

A wheel also doesn't look very palatial on the outside and seeing as in your version the throne room isn't part of it (the whole thing is more a Royal Yacht than a palace going by the scale) we never see what it looks like on the inside either.

I'm all for putting a big Imperial seal on the top as some kind of decorative feature (an observation bubble in that shape would be cool) but your wheel design (great as it is) looks more like a space station than a floating building capable of space travel.

Maybe if you took the seal shape but gave it more variety in the third dimension so it looked more conical from the side on than disk-like and only resembled the seal from above or below that might work more.

Something like a spinning top or a Roulette wheel but not as flattened out as Cloud City and the throne room prongs could come out of the Palace and settle on the tower rather than the other way around.

As you present it it's a fine Royal Yacht design but if you are going with that approach you might as well have a fancier looking shuttle and keep things roughly the way they look now.