You guys are missing a huge point. Being with the inquisition and weather or not he fell in love with her DOES show him the good in this new world. He's obviously conflicted from the moment he meets the inquisitor especially if she is elven.
The whole point of the ending was to say " is he conflicted enough to find another way" unless you was a complete dbag to him the whole time then of course you chose the destructive solas. It's all in the matter of how you rpd it. The choices you made. Everyone is looking at it as finite. When we all know anything can happen.
Also for the record Solas does try and find the good in this new world. And he was shunned at every turn. By his own people as well as humans. Varric was probably kindest to him since his awakening. THAT is why he set out to repair what he seen broken. Because this new world is to self absorbed too entangled in racism and fear of mages and this that and the other. To power hungry not loving enough. As I said I would hope peace could come but.... without unity there is no peace.
Being a dbag= taking the mages as "prisoners" and not as allies, cuz taking them as the latter completely makes sense seeing how they allied themselves with Tevinter, Fiona's attitude and their general behavior even before that (which ranged from utter stupidity to "please, take us into your custody. PLEASE"). Not allowing an order that has been fundumental to the world to just get thrown around because "HOW COULD THEY- righteous rage of the screw up elven god". The Well, and that whole situation just talks for itself.
In short, ask questions to Solas and he'll be mildly amused by the Inquisitor, do something he doesn't like and enjoy getting judged by someone who, clearly, has the high-ground on everything that is morally right and ethical
Also, he woke up one year before Inquisition and in that time he made some kind of organization, made a plan to give the orb to Cory and acted upon it. I'd say that would take something like 6 months, so his schedule once he woke up was something like this, probably:
January-March: try to convince some elves of some clan to abandon their centuries old beliefs in favor of the word of good ol' great me. Possibly fail so i can at least say "i tried"
April-September: make a very smart plan and, this is important, absolutely learn nothing of the different factors that could screw it up
October-December: find a wolf pelt to put over my sentinel armor
This without considering the time he spent in the Fade, nor his travels to ancient ruins (that he did as a hobby while plotting to kill everyone)
ALSO, if anything the Dragon Age games showed me that Thedas, or at lest the South, can and will unite against a common enemy, that the good far outweights the bad. What has Solas' great lost civilization has shown me? That power-hungry, slavers egomaniacs were in power AND that destroying everything was the only way to get the world rid of them (and when i say, i try to see it from Solas' POV, since his defition of "only way" is quite arguable)
He specifically gets mad at the Wardens for thinking they can solve the Blight problem by going after the Old Gods and killing them before they become Arch Demons. That's a clue that he knows more than he's letting on about the Blight and its relationship with the Old Gods.
Or, it's a clue that he's a major hypocrite, judging people who tried to do good and were twisted by others to do evil, while he twisted himself into doing stuff like that and worse in the name of some lost civilization
One or the other, really 