Depends on what my siblings wanted to do, and the sentimental value of the guns. If they meant a lot to all of us, of course we'd split them the best way we knew how. If they really weren't that important, than I don't see why selling them would be a problem.
As for determining values, you can always post descriptions (and pictures! LOTS of pictures!) here on THR (in the appropriate sub-sections, of course) and let the many, many knowledgeable folks here help you out.
Or, if you know the make/model/serial/year of production/etc of the guns, you can use Google to search for info, or auction sites (Gunbroker, etc) to find what kind of prices comparable firearms are selling for.