Thanks Marty, I appreciate the feedback and the positive energy!
I assume you convert each RAW file to TIFF, or do two different versions of the same RAW file and convert them both...
So then you have two open TIFF files in your photo editing program window. In Photoshop I pick one image to be background and one to put on top of it. For the one that goes on top of the background I do this: select all, copy, then close without saving. Now the background image is the only open file. I select all and paste into. After that, for starters, I'll usually switch the new layer from normal to luminosity and reduce opacity to 50%. After that initial look at both images together I can get a sense of exactly how I might best combine them using all the other tools available. There are certainly other ways to do this and hopefully somebody will come along and share.