I have very wide seat bones, so I expect to replace the saddle as a matter of course. The general rule of thumb I've found is one size up on what "should" be on there, i.e. sport saddle = touring saddle. Keep in mind that as you sit up, your hips shift, requiring a wider saddle: This is why you see massive saddles on cruisers and tiny ones on race bikes.
My favorite is a Cloud 9 suspension saddle, like this:
http://www.amazon.com/Sunlite-Cloud-...5090370&sr=8-1
At the time, I had a large Amazon gift certificate I needed to spend and figured I'd give this a whirl based on the reviews and it's larger-than-average width. The gel is a LOT stiffer than most saddles of its type, the springs are of adequate strength for my clyde weight, and the shaped top supports my butt bones perfectly. I originally bought it for an old 3-speed, but it's currently on my hybrid, which is my long distance bike. Even if I spend time riding dirt roads, my butt still feels fresh long after I've worn out my hands and wrists.