http://www.wbdg.org/design/spacetypes.php is a great resource for the specs & considerations of a variety of building plans/uses. You have to dig some to find the actual building plan concepts, but here's one such document:
http://www.wbdg.org/pdfs/gsa_usc_shell_courthouse.pdf includes cost/needs analysis, some pretty hand sketches of concepts for courthouses. One could easily use these sketches directly, or map them on grid paper or on a computer, use the ideas for 3D modeling, etc.
http://www.cmu.edu/cdfd/documents/masterplan2002.pdf found this through wbdg.org by following some links and noticing this PDF as one of the "case study" examples. Has maps of Carnegie-Mellon U. and expansion plans/maps, etc.