On a sidenote, I'm kind of looking at Cass as his female equivalent.. although not entirely. I kept thinking of her with a warrior or mage, but maybe rogue would be cool too. For some reason, Alistair seems more flexible though. There's a lot of stories that seem to click with him (kind of how I see Leliana too).
I did Cass with a human warrior and a elven Mage. They look are so girly to look at though (my CC skills aren't the best. And I play the Sims 4, so I should be better with my CC skills but I'm not, I'm horrible at it). I'm just relaying that i have horrible CC skills but love the Cass romance, and I have two men doing her romance, I think it'll do a Male Human Mage with her next (cause Mages are the best class to play!)
But anyways, to Alistair,
I really liked his romance and had ruthless enough females (besides for the practical Broska and my Leliana romancing male Cousland whom kept Loghian alive) that killed Loghian. My Female Amell was very smart, but had such a 'keep everyone alive and well!' Personality that she let Alistair kill Loghian himself (not dueling, she dueled him. And it was fair, she's an Acrane Warrior with a sword and shield). She just let Alistair kill him and let Anora be queen. My Canon Cousland? Nah, she was all fair and just. She dispised Loghian ruining Ferelden and selling elves to Tevinter Slavers, It digusted her to the point where killing him was her goal in the end. She killed him herself, and went on to becoming Queen Consort with Alistair.