As a skier, I've become used to the idea that ski boots being frequently extensively modified for to provide a very snug but comfortable all day fit. My own boot liners I've modified with extra pads of special fitting foam and look awful but are indeed comfy. As a compulsive tinkerer and modifier, I've approached saddle comfort much the same.

Like you, I despaired of finding happiness in a bike saddle and went through a number of them with little success. Half way through the summer and 4 saddles later found one that was not perfect but but not bad either, at least for my distances. At that point I began modifying by cutting a slot in the nylon/plastic base material to soften the center area that usually has the slot. This helped a lot. Next I shaped a board to what I thought my butt would like. Then I clamped the saddle to the board and applied hot air from a heat gun to reform the plastic to the board. This took a fair amount of heat as nylon softens around 200 degrees F or so. Success. This saddle is now close to perfect in that hours of riding can pass before noticing the saddle. I enthusiastically recommend tinkering with gear.