There is a lot they could add in a Val Royaux DLC to make show it off. Some suggestions.
New Companion Quests
Most companions I can see easily tying into a section of the city, thus giving us a reason to go there; each area should have say 3 quests to them not counting the companion quests. Here are my ideas.
- Varic: A noble Quarter similar to High-town, though could easily be something like low town. His quest would be about the merchant's guild and the carta. Dwarven inquistors get extra content here.
- Cole: The white Spire. This is so important to who cole is, I am actually surprised that we didn't go there for his companion quest. Human mages would have some extra content here.
- Sera: The slums. Sera is out for the little people, so why not her quest be something like mark of the assassin, a heist from a noble house to help out the 'little people'
- Cassandra: Grand Cathedral/seeker HQ; as the companion most tied to the chantry, lel is an advisor not companion, going to the grand cathedral can tie into her quest. Also if she is made divine for her to be crowned her. Human rogues/warriors get some extra content here.
- Iron Bull: The area, not sure, maybe a lower class region? But the quest would be for him to show off his Ben-hasrath skills, assisting him on a job for either the inquistion and/or the Qun. Qunari would get more content for them.
- BlackWall: Not quite sure for blackwall.
- Dorian: University of Val Royauex or the noble quarter of Val Royaux. His quest
- Viveienne: The imperial Palace, she is the magical advisor to the royal court. Her quest would be about just that, some extra opitions if Gaspard is in charge.
- Solas: Hard to say, but I say tying him to the alianage is best. Solas does care about the elves, in his own particular way. Plus this might be motivation for him, as the alianage of Val Royauex is supposed to make the Denerim one look like a paradise. extra content for elves here
Showing our Choices
This is probaly one of the more obvious ones, but a good way to show our impact by what people are talking about and things you see. Some random examples.
- before the civil war ends, you might have to deal with a gang in the slums who are supporters of either side.
- after it is over, everyone is talking about it. Town criers are shouting about the outcome.
- Showing some of the war-table missions and effects; for example there are a number of missions to determine alliances and arrangements in Orlais, let people talk about them here.
- Templars: after Ser Barris is promoted to knight-commander of the templar order, you can find him at the templar hq. He would have a quest or two for you.
- Mages: first judging fiona(
) second, perhaps the white spire becomes the hq for the college of enchanters and the leader of the mages can expound on their plans.
- Seekers: disbanding the seekers might show the seeker hq falling appart or changed to a different building. reformed and kept would show it slightly different.
And of course lots of new quests. 
so what do others think of these ideas?