MeetingMatrix is a Windows-only application for laying out furniture in hotel function rooms. They provide very detailed (and they claim accurate to 1/4") maps of function rooms at hotels. MeetingMatrix is a bit confusing to setup (and you'll need to register to get a license key use the program).
Once in MeetingMatrix, you can drag and drop tables, chairs, and other furniture into the rooms. The finished maps can be saved as JPEGs (or in other formats).
MeetingMatrix Silver is free, but it doesn't have all of the features of the commercial versions (such as the seating wizard which automatically lays out rows of seats).
In the city of Boston, Massachusetts, they have detailed maps for 76 hotels and venues.