Shopping Centre

I have been looking at the layouts of buildings to gain an understanding of how to structure my shopping centre, for example the university:

For the demo I will not have to make the whole of the shopping center, with all the little details such as the insides of the shops with all the individual objects and commodities, however the actual base and structure I may make so that the player can raom around freely without being restricted by the demo, however the player will not be able to go inside all of the shops, perhaps just a few so that they can find an object to fend off the creatures with. there will be a warehouse which will be very basic and there will be a security office available. I appreciate this is alot of work but it will all be very basic and not too big.