Another vote against the tractor seat here, for all the reasons given - you'll be way less stable on that seat, and I'm betting it will really only be comfortable when you're in an upright position riding on easy, level terrain.

I've been using the Specialized "body geometry" saddles on my bikes (a Bianchi cross bike and a Bianchi road bike); they are pretty slim and minimal, but have a cutout in the middle to take pressure off of your perineum, and they come in different widths to match your body's sit bone spread (they even have a gel thing you can sit on in the bike shop to measure your sit bones).

Did a 45-mile bike ride yesterday on a road bike with the "Toupee" model and had absolutely zero soreness - great saddles! The Phenom and Alias models are similar in concept but made for mountain and touring bikes.