The weekly perfect challenge achievements seem like good candidates for boosts:
Week 1: A Perfect Introduction (Eloquence boost)
Week 2: A Victory of Leadership (Leadership boost)
Week 3: Marvelously Misjudged (??? boost)
Week 4: Miracle Worker (Insight boost)
Week 5: A Star is Born (Charisma boost)
Week 6: The Lady, the Legend (Grace boost)
Week 7: Legendary (Cunning boost)