I've seen a lot of half elf warlocks (as their abilities fit those best) and they tend to take as their dilletante power anything that is keyed off Cha or Int (since Int is a strong secondary requirement for all warlocks). This means that wizard powers are most popular, and especially scorching blast as warlocks don't get many area attacks.
I'm planning on bucking the trend with my half-elf starlock, who will be taking the ranger "Hit and Run" as his dilletante power. His Str is rubbish, so he doesn't expect to hurt anyone with his pact dagger using it, but the "effect" means that it can be his 'get out of dodge' trick - whether I hit or miss, I can move away from the target without provoking OA, which is a neat trick for a ranged guy to have.
Generally speaking any of the Str to hit classes have an easier time of it because they can pick a dilletante power from any of the other Str to hit classes (fighter, paladin, cleric, warlord, ranger) and have a good chance of it working. Occasionally a strong secondary ability can give nice synergy (e.g. a Fighter specialising in Hammers and with high Con can benefit from Infernal Rebuke: Con to hit and there is the extra damage if they hit you, which is nice).
Cheers