How do I get my Revit model to a PDF file?

The best choice is actually Bluebeam Revu as it also allows you to collaborate on the PDF with multiple users simultaneously with mark-up functions. You can get a 30 day trial of the CAD version (necessary to work with the Revit Plug-In from http://www.bluebeam.com/us/partners/network/hagen/cad/

The model can be opened via IE8 or just download a DWFx viewer add-on for Firefox. See http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=14683283&linkID=9338138.

You can actually convert a 3D DWF straight to a 3D PDF file. Revit > DWF > Adobe Acrobat > PDF 3D, but if you want to use DWF do this: Revit > Publish DWF

I like CutePDF or PDFCreator (for batch prints). Also check out the posts at:
What Revit Wants: pdf

Print as pdf with Nuance PDF Converter Professional or adobe or any other pdf writer