I have always tried to level a saddle by using a hard back book and a leveler. Make sure the book covers the saddle evenly and try the leveler. That's my take, I know guys that can just eyeball it, me not so much! You could also try the leveler next to the rails. For what it's worth, I have a Bontrager affinity RXL on my bike now and had to go above level with the nose. The dip gives it the optical illusion that its higher than it is. What a difference a level saddle makes!