I know right now I am not letting him live but I find myself getting bored with the Alistair romance and I feel myself getting ready to go to the dark side. I was thinking a dalish scout elf but really they would kill him for enslaving elves. I'm not really into the dwarves. So I have to have a damn good reason for a mage or especially a cousland to spare him. The problem for me is that I have yet find a character who could justify not killing Loghain especially against Alistair because as much as I can play a character who might use Alistair or find him annoying, I don't feel any character could be okay with trading Alistair for Loghain. As annoying as Alistair is, he's still a decent guy. I know people hate him but I've yet to find a single reason to trade him for Loghain. Even if I loathe the wardens and want them to cease to exist for cursing people with the blight through lies and manipulations I don't feel that there is a single character I could play that would logically be able to pull it off. Furthest I could get is Alistair is a brainwashed dope who whines a lot and can be a bit pathetic at times, but he's not a bad guy. I guess if I could run a male cousland I would let him live for a power grab at the throne but I'm not into playing a male when I can play females. That's part of the problem. The design of the choices is such that playing a female sort of tilts you away from Loghain or at least it does for me. For a male there's grabbing for Anora and not pissing her off with her dad and saying screw it to alistair because he's in the way but the female gains nothing. There is no actual motivation to let him live. If I want the thone, I get it and use Alistair as my puppet (screw what the slides say... I brought us victory against the blight, I avenged my family and I was raised by Bryce Cousland. I can damn well make Alistair my puppet king. And actually, they really should have slides for that... can I change the slides?)
Elves aren't a single entity, something pointed out in the other thread about the deals magister Caladrius offers. Remember, Dalish do look down upon their "flat-ear" urban brethren, despite them being of the same race.
Mages are a special case in and of themselves, so the mage origin PC, even the elven one, may have no empathy for the enslaved elves.
Couslands are the toughest case, it's true, given that they are invariably put at odds with Loghain's accomplice, Howe.
Good thing you are pointing out the power-politcking reasons as for why fémme human Wardens may wish to hold on to 'stair. Myself, I feel content that my Warden missies can witness the rise of a "virgin" Queen to power, brought about through their actions.