We are using pdf995 version 8.2s and pdfEdit995 to produce 11x17 pdfs. After a lot of trial and error we have figured out how to produce 11x17 landscape oriented pdfs that DON'T require rotation by the end user.
1) In pdfEdit995 go to the rotate tab. The upper portion controls pdf995 - pick "Rotate all pages" (Ignore the bottom portion. It is for rotating existing pdfs and rotates the last created pdf.)
2) In AutoCAD pick "Landscape" AND "Plot upside-down".
This seems odd but it works for us with AutoCAD 2005.