I have 6 years experience designing layouts for MAGFest, a 20,000 person videogame music festival at the Gaylord National Hotel in DC. Below are some example renders done using Sketchup+Layout. Floorplans were either provided by the venue or measured by hand and re-created in sketchup. All of these are full 3d models that can be rendered and shared easily.
Full disclaimer: I have a lot of experience creating detailed drawings that are great for event layouts, compliance with firecode/crowd flow, and for 3d visualization purposes. If you need floor plans for construction purposes or for extremely precise applications, you may require further services from an architect or engineer.
Video demo below:
Gallery of Sketchup floorplans below: