A natural consequence of lighting buildings is that you also need to put something inside of them so your not just lighting up empty plastic shells. Well, that's not entirely true. You can block out the windows, either by making them opaque (so that light shines through) or use window coverings (that give the look of draperies, which are typically provided with a lot of the German plastic kits), which is a technique I use frequently enough. But I think we all would agree that actually showing some detail is preferable in some cases!
One of the main lessons I've learned about interior lighting is that where you put the light is critical. Its really important for the LED to be as close to the 'window' as possible - in other words - you want the light to shine on the same surface of your interior design and details as you would 'see' it when you look in the window. The reason for this is fairly obvious (at least after you create, light and install an interior); if you put the light 'behind' your subject, you will put all of your detail, figures etc... in shadow, which is not really the effect that you want to achieve.
The detail on the ground floor is made up of two different approaches. On the right side is a "Mos Burger" restaurant. You'll note that it has different color lighting from the store on the left. I used 'warm white' LED's for the restaurant and 'normal' (?) white LED's for lighting the electronics stores. Seems to be right I think. I also color/paint the floors separately to add further differentiation.
Furniture is primarily basic, cheap-o N scale benches while the tables are just bits of styrene glued to small 'cubes' of foam-core, or random bits of thicker plastic. Whatever is handy really. Everything gets a bit of paint to make sure its reasonably appropriate. For the walls, I try to use whatever I already have...usually no one can read the signs on the walls, so the idea is to put something there that might look okay, but doesn't have to be perfect.
I had a lot of fun with the ground and upper floors on this building, but some of this work was wasted. n the ground floor I included both a hobby shop and a pizza parlor. The below image shows the ground floor before installation, and you can get a pretty good idea of the standard techniques I use to create interior furniture, etc....
I'll continue to share some of these, hopefully this is interesting to see! As you can tell, I try for a certain level of detail and then stop...my philosophy is to give the impression of reality, not to try and duplicate it. At some point I would like to try and commit more time and effort when the list of 'to do's' is much shorter than it is now! Hopefully I was able to share something of my work that is at least interesting! Thanks!