From Chapter One, Races: I've used Racial Paragon Classes and the Environmental Races. I'll still use Environmental Races in the future.
From Chapter Two, Classes: I've used Monk Fighting Styles, Spontaneous Divine Casters, Battle Sorcerer, and a variant on Prestige Paladin. I will use all of these again in the future.
From Chapter Three, Building Characters: I've used Weapon Group Feats and Craft Points. I will use Weapon Group Feats in the future.
From Chapter Four, Adventuring: I've used Damage Conversion, Massive Damage, Death and Dying, Action Points, and Players Roll All The Dice. I'll likely use them all in the future. I have to admit, though, that I Grim Tales' version of action points to be much more satisfying and will use that version in my games.
From Chapter Five, Magic: I've used Legendary Weapons, and I am undecided about using them again. Also, I am going to be using incantations in the future.
From Chapter Six, Campaigns: I have used Reputation and Honor. I wil not likely use them in future games.
From the DMG Variants: I've used Striking The Cover, Automatic Hit and Misses, Critical Misses (Fumbles), Critical Success of Failure (on skills), Power Components, Free-Form Experience, and Less Lethal Falls. I will likely continue to use these variants, though I may drop Less Lethal Falls.
For the most part, if I tried something and I'm not using it in the future, it simply didn't give me what I wanted or wasn't used by the players.
Hope This Helps,
Flynn