What I am proposing is a small list of feats for fighters that can only be taken at fighter level 20. The purpose of these feats is to enhance whatever fighting style the fighter chooses. I've noticed that some of the most potent class, monks and favored souls, for instance, gain something useful (like Damage Reduction) at level 20. The fighter, however, only gains the same benefits that half the previous fighter levels had.
1) Tactical Specialist: You gain +4 to the DCs of tactical feats, and gain +1[W] when using them.
2) Defense specialist: You gain +5% to AC, 10 PRR, and an additional 10 PRR when using a shield.
3) Offensive Specialist: You add +5 damage to all attacks, and an additional 5 when using Power Attack.