There's not much info to give honestly. I don't know the latest AE spots but leader AA is all about the quantity of exp messages not really the individual mob types (though the level / zem does affect it to a point, its minimal compared to the intake). Basically just ae spells/stuns with a tank and a healer or two in whatever area you can still gain exp.
The actual quest I was referring to is found at the link below, no idea if it still yields exp at 75, but it was great at 70.
If you do Ashenback, try to get mentor. The eggs give pretty good xp, due to the quantity of them during that fight. I think Oblivion in Sunder was pretty good, as well.
Head to the sewers in the SkyLance missions. You can pull a ton of mites at once and they die quick to DSs and Burning Aura. I think I used lingering sloth to make sure they did no have a no-aggro death, that or light heals from cleric. It has been awhile
As a bonus, every once in awhile they drop a 70 hp/man aug with 40% haste.