I'd like to see improvements upon the system on a fundamental level while keeping resources in check.
1. Change the tag of "outdoor furnishing" to "indoor/outdoor furnishing". This will allow for better management of inventory, increase decoration combinations indoors, and allow gardening for those that couldn't afford a plot.
2. Add new layout presets that can be purchased for half the cost as if you had bought an equivalent plot. For example, you could buy the interior of a small (1.5m), medium (10m), large (25m) and they would naturally come with the storage increase already built in. If you relocate to another apartment or plot, you keep the upgrades you bought. Additional layouts can be bought for their respective prices, and you keep them unlocked if you decide to change the interior. Buying the plot would already have the base layout unlocked if you didn't have it already.
3. Apartments are the base size of an FC room. With new layouts, you can make presets beyond what is already in the game, like having a small with stairs leading upwards instead of downwards, making the room twice the size as a square or twice as long as a rectangle without the stairs, keeping the combined size the same as a small. You can do similar layouts for the medium and large versions.
4. These changes can also be applied to both plots and apartments, further enhancing ward usage, which would reduce the need to swap locations unless you prefer a closer marketboard, a different outside view, or just a bigger yard.