I have a document that is over 100 pages and in it is a table that is oriented to landscape. When I save it as a PDF the table defaults back to portrait orientation. How do I get the PDF to recognize the landscape orientation?
You didn't say what version of Word you are using, but Word 2010 produces a PDF that honors your selection of page orientation. So if in Word the table page is Landscape, the PDF will be made with a landscape page. Help on saving Word to PDF. [I mention Word saving as PDF because many people that have Acrobat installed will see a menu option called "Save as PDF" which uses Adobe Acrobat to make the PDF, however, (in my experience of older version of Acrobat) the PDF made doesn't link within the document (table of contents, cross references, and the like), and isn't done as well as Word].
If you don't want to/can't make sections in Word to change the table pages orientation, than you can always change the PDF after it is made using any number of free tools (e.g. PDFTK). If this is a document you will need to maintain (revise) over time, using sections to rotates the table pages may be faster in the long run.
The downside to using sections to rotate the table pages is page numbers will be at the bottom of the landscape page, not to the left/right depending how you want the table page to be rotated. In that case you would need to use a text box to hold the page number for that page.