Over at the Arcana Wiki, I have started to collect links to floor plans of suitably generic buildings. These are organized into the Architecture section, and so far I have floor plans for the following types of locations:

- High-rises
- Hospitals
- Libraries
- Shopping Malls

You can use these as inspiration for your own maps. Or, of course, if you know of any such maps yourself (perhaps you have even created some), you can add links to it to the wiki, possibly by creating an entry for the relevant location type first (such as "castle", "warehouse", and so forth).