Some of the half-elf dilettantes have some interesting possibilities, but I think they could do with an update that might make the race a bit more tempting for various builds, so here are some suggestions:
Artificer: crossbow and repeating crossbow proficiency. Improved Dilettante tier 4 lets you wield a runearm, although of course you only count as a level 4 arti for runearm damage.
Barbarian: Instead of a trivial amount of damage reduction, you get proficiency with all two-handed martial weapons and 5% bonus run speed. Improved dilettantes add 5% glancing blow damage and 3% ability proc, small amount of melee power.
Bard: Proficient with all light weapons. All abilities that create a stunning effect last 2 seconds longer. Improved dilettante adds +1 crit range with any light weapon.
Cleric: Multi-selector. Choose a domain ability. Tier 4 improved adds another ability of that same domain.
Druid: Character must have a Neutral alignment. You can transform into a basic wolf or bear with the core wild shape abilities only. Druid Oath limitations apply. Improved dilettante allows water and fire elemental forms.
Favored Soul: Deity multi-selector. You are proficient in that deity's favored weapon. You get +2 HP and +5 sp per level. Improved dilettante tier 4 lets you select wis or cha to hit/damage with your deity weapon.
Fighter: Proficient with all martial weapons and shields. Improved dilettantes let you add +1 tactics DC's and +5 PRR
Monk: Character must have a Lawful alignment. You can add 1 point per character level of Wisdom to your AC when centered. Proficient with Kama, Shuriken, Handwraps and can attack with Handwraps as a monk. Improved Dilettantes: Multi-selector lets you take the modal half of monk Form feats. Centered limitations apply. Does NOT give you a Ki bar.
Paladin: You may add 1 point per 3 character levels of your Charisma to your saving throws. Improved levels add light damage (scales with melee power) to your attacks. Bonus heal amp.
Ranger: Select TWF or Ranged. TWF gives you 15% base offhand proc, with each Improved Dilettante giving you an additional 15% offhand proc for a total of 60%. Ranged: you can add 1 per level of your strength to bow damage. Improved ranks grant 10% ranged alacrity or 10% doubleshot. The effect does not apply if you have the Two Weapon Fighting feat (whether taken or granted from class), or if you have Rapid Shot (taken or granted from class).
Rogue: +1d6/5 levels sneak attack damage. Overwritten by rogue sneak attack, but works with other sources of sneak attack. Improved Dilettantes grant fort bypass.
Sorcerer: Choose an element. 30 spellpower and +10% critical damage with spells of that element. Improved Dilettantes add more crit damage.
Warlock: Choose a damage type (fire/acid/sonic). Gives you a Pact feat that adds 2d4/4d4/6d4/8d4 damage of that type to attacks and spells. Scales with spellpower.
Wizard: +1/2/3/4 spell penetration. Choose a school. +! to DC's and caster level of spells of that school. Additional +1's from improved dilettante feats.
So, they'd potentially be quite valuable and maybe even allow for some builds that wouldn't otherwise work well. But it'd also be kinda expensive. But it would also mean that half-elf might actually be "best race" for some specific or unusual builds.
They're just suggestions, surely most or all could use tweaks.