jlwoodward,
I have a very strong preference for sending out full sized paper copies of my drawings. The paper copies contain exactly what I put there using SolidWorks. My details and fonts all are big enough to be readable.
Unless the part is very simple, our machine shops always call and ask for DXF files. I do not trust the special character fonts and tolerance specifications in DXF files. You have no control over the software the other guy is using. I do have confidence in the scale 2D drawing, which machine shops use to program their CNC machines. I send them the DXFs addition to the paper copy. DXF files are large, but they compress very will with WINZIP.
If I could not send paper, my next choice would be PDF, but I do not think our vendors have E size printers.
Our sheet metal vendors asks for SolidWorks files and models. They want to get at SolidWorks' sheet metal features,which I used to create the model. I send the SolidWorks drawing and model. I assume that all fabrication drawings and models potentially go out of house, and I keep proprietary information off them. These often get large enough that they do not fit through email. I have to burn them to CD-ROM.
What you send through email has a lot to do with your vendor, and his expertise and resources. I just sent out drawings of a flexible cloth cover. The vendor knows nothing about SolidWorks, DXF, or DWG. They have Corel draw, which I do not. They did manage to read my PDF file, but I do not think they have an E sized printer. I sent paper. Also, I sent JPEG files of the part to help them visualize it.
Stereo laser lithography vendors like STL files, which SolidWorks generates. I would still be inclined to send the SolidWorks file, and let them do the coversion.
JHG