A Stereotypically Good Warden:siding with Bhelen
The greater good is a concept that is often misused for "being a total dickhead", but it's one that can be used right. Your Warden wants to end Orzammar's isolation, improve surfacer/dwarf relations, and he wants to end the suffering of the casteless. And maybe in the long run help restore a civilisation and save lives! This'll be easier if they're a touch pragmatic and might not work for a character who is good and either incredibly idealistic or kinda stupid, but you can always have them not pick up on Bhelen's deviousness. If they're a Dwarf Commoner, they want to help their sister and not plunge her into darkness and kill her husband. All valid motivations for a stereotypically "good" character.
romancing morrigan
Your Warden cannot control their own heart, dear Hero! I hear good people, they follow
their hearts. Besides, heroes have a habit of doing
this sort of thing (I could link more tropes like those if I could be arsed). Remember: just because you lie on two different ends of an alignment spectrum, doesn't mean you can't bump uglies or snog. Romancing Morrigan is hardly an inherently evil act.
sparing loghain
You can call out a lot of words to cement your status as a hero, but alongside "For honour!", "Duty!", and "Justice!" is "Mercy!". Well, it doesn't work quite as well as a battlecry, but "mercy" is generally considered a good thing, no? The Warden believes in redemption! Loghain should get a second chance, to put things right.
Or, you might think, you know what? Killing is just
wrong. Whether they be heroes or your most dastardly villain, it would be just wrong to kill them. Admittedly, the Warden has killed so many by now, but I am like 96% sure most of those people just attacked you and threw themselves at your sword/daggers/arrows/staff(?). Self-defense, right? Incidentally, a Warden like this should probably spare Caladrius, but without doing the blood sacrifice for very obvious reasons.
doing the dark ritual?
You know what? Morrigan's been with you through thick and thin. I'm sure you can trust her, especially if you romanced her (warning: I do not actually think this). And you don't want to risk the life of your fellow Grey Warden. You have to do the Ritual to make sure they live (even if they're Loghain). This'll be easier if you're male, since you won't have to try and coerce them into sex (and if you are female, it'll probably be easier with Alistair, who is a bit less willing to die to atone for a bucketload of sins). But even if you are female-inclined, convincing them to save their own life is good too.
how about using blood magic to save connor instead of getting the mages to help?
What? You want to kill
a child? If there's an alternative to that, we should do it. We can't get to the Circle in time/I had to let the mages be closely examined for demons in order to ensure no more innocent deaths in the future, but who is the good guy Warden to stop a mother from sacrificing herself for her own child? Her life, her choice. God bless you, Isolde!
Alternatively, greater good, you've got to eliminate the Orlesian accent. Long-term justification, will improve the lot of all Redcliffians greatly as time goes on and there isn't Isolde's voice in their ear.