Battery shop model

My next model is a battery shop.  As usual I installed details inside the shop area which are not visible in the photos but you can see them in person.  I placed a large battery sign on the roof to add a nice colorful detail.  The front door and two windows are commercial parts.  The back door and left wind are scratch.  I added a bunch of signs on the walls.

The interior details include a work bench, shelves with batteries and other things.  I also built a wheeled air compressor.  You can see one of the batteries inside the right side of the door. 

Below is a rear view of the model showing the ladder to the roof and rear door.  The roof is flat and "tarred".  

And now I need to come up with an idea for my next model - something that gets harder and harder as I have built so many models.