This is the method I use although I only archive a few JPEGs.
The third way, and the best of both worlds, is to set the camera to monochrome picture mode and shoot both JPEGs and raws in-camera. The JPEGs mean you have mono shots for immediate use and also proof images that can help when you process the raws. Essentially, this option is win-win with the only downside being the memory needed for shooting and storing two files of every image. This is the method I use although I only archive a few JPEGs.