Thanks to a thread on eGullet, the foodie's equivalent of the Bullshido forum*, I found Broker's Bitters. It's amazing how much it improves a Manhattan and the complexity of flavor it gives. Adam Elmegirab sells them from his Evo-lution Bar Consultancy: shipping is quick and service excellent.

2 shots of 1792 Bourbon
1 shot of King Eider's Dry Vermouth
1-2 good dashes of Boker's Bitters
1 dash Tabasco (optional - but Dad liked it that way)

Shake with crushed ice and pour off the liquid. (If you use ice from the lab freezer at -40 C, it works really well.) Add one Maraschino cherry.

UPDATE: Broker's Bitters has a very very diiferent flavor in the drink than traditional bitter. Where the normal bitters have a citrus scent, Broker's has a very evergreen or spruce-likely scent with more stronger hints of other flavors. The range and depth of flavor is amazing larger. One  has to wonder if cocktails would more popular than those nasty sweet drinks if more bitters tasted like this.

* You are officially warned.