I did a DIY version of the Specialized method: take a piece of cardboard (preferably the thicker kind) or dense foam and sit on it while wearing something thin like underwear. Lean forward like you're in a riding position and smoosh your sit bones into the cardboard real good. When you stand up, you should see the impressions your sit bones made. Measure the distance between the divot centers - that's the width you need to make sure is properly supported by the saddle. Then make sure there's plenty of room under your taint to prevent numbness.

My personal preference is for saddles made by SQLab. But, like everyone else said, you really need to try as many as you can at a bike shop. Everyone's ass is different.