This (SMB Share) sounds like your uses are running MS Windows. If this is the case, PDFcreator is an open source print-to-PDF virtual printer driver for MS Windows that my employer has authorized us to use. Because it runs on the user's PC, the user can save the file directly to her/his PC with whatever name the user chooses.

For Linux, the applications I use can generate PDF and/or text output. If text, I then use enscript and ps2pdf to produce a PDF.

Of course, if the applications are producing text output, you could setup a print filter that uses enscript and ps2pdf. (Or, better, 2 filters, one using enscript to generate PostScript and the second using ps2pdf to convert PostScript to PDF. This would allow your CUPS server to accept PostScript as well as text)