We use Excel 2011 for OSX at work and we are consistently encountering the following problem. When we have a multi sheet(page) workbook(document), with both landscape and portrait pages, an error occurs when we try to go to export to a PDF file (file > print > pdf). Instead of generating a multipage PDF file Excel will generate each sheet as a pdf. We can of course combine these back into 1 PDF file once generated in Adobe Acrobat,but it's a fiddly work around for something thats pretty basic and works fine (generates a single PDF file with all pages) in the Windows version of Excel.
I've attached a sample excel file if you want to see the problem first hand. : - https://www.dropbox.com/s/enrgch3znd4z89n/sample%20excel.xlsx