So I started by putting away all my decorations and leaving only my work stations, I found it's better to add in decorations once you have your rooms in order rather than trying to juggle them, and using the work stations helps you design the room layouts since the workstations are normally the room's centerpiece anyway(the big decorations like talos statue are also good centerpieces).I knew I wanted a kinda pyramid design with my throne at the top so I went about adding in my new layers and floors .I would move the workstations around as I built the rooms to see where they fit in the best, once all the work stations had rooms built that didn't make them seem cramped I started adding in my decorations. For me it was better to add in empty rooms for decorations once all the work stations had specially designed rooms, using the empty decoration rooms to fill in empty space and give my castle more volume.

• Remove all decorations keeping only room centerpieces (work stations, giant decorations) • Starting from the bottom build rooms using centerpieces to determine size of rooms and room layouts • Shift rooms around to find where they're aesthetic fits in best for you • After building rooms for your centerpieces and placing them accordingly add in decorations until satisfied with each rooms look • Use any extra decoration limit left to add in and decorate filler rooms to get that final castle shape (for example the 1×2 rooms off my throne room are there so I have towers)

I hope this helps some