Find someone with a portable bandsaw and hire them to quarter the biggest ones and half those that aren't big enough to be quartered.  Then you have straight sided posts with a really smooth side minus the splinters.

If there is enough to keep a bandsaw busy for a couple of hours it should cut the cost per post down to a justifiable amount and you can save the labor you would have used splitting them for building fence.

If you end up with more sawed posts than you can use, you can sell the smooth sided posts to someone needing to build a corral.  Think VALUE ADDED.