I'm usally more for story DLC, but there are some things that could be connected to story DLC too and I'd really love to see.
1) A "wolf hunt" DLC. Solasmancers will understand.
i would be happy with simply more scene and conversations with his character. I'm not asking for romance-specific content, or sex scene. I'd only like some more interection with the character. we hardly have a few cutscene with him after his mission "all new faded for her".
2) Hairstyles!!!! For all races!!! and NO BALD SPOT FOR FEMALE; THANK YOU VERY MUCH!!! I can't use the half shaved/ half long hairstyle because the bald patch irks me. And is the only long style I would consider. Not that the short ones are better. I have problems creating a new elf character because I can't stand any of those.
the only less horrible hairs are the pixie cut (I love the kind of hairstyle, but is quite bad realized, expecially if one look at cassandra's or Sera's haircut.) and the 80's 
Let's not talk about the female Qunari. I still can't understand why hair (as horriblem and few as already are) and horns can't be separated. Is very limitating having hair and horns united.
3) Please let us change clothes in Skyhold. or at least the color. That beige thing is horribly bland (and totally out of characters for Qunari and Elves. If it is too much work, let us wear our harmor ot a mage dress.
4) A cest is needed. I hate having to sell unique items, or having the inventory full of things I can't use because I'm still at a low level to use it.
(I know, I have out there six, ad not five. But since those are most gamey fix...)
5) Since I have romanced Solas after the second kiss I didn't even needed to enter in my Inquisitor room.
So there are two chances: or give us some more things to do in these quarters (like kiss that sexy elf when we like, like the ohers romances) or at least put something interesting to do there: like some scene there with the companions (like in ME3) a minigame or something.
6) a mirror of trasformation like in DA2 (one of the few things I liked of that game), since the light usually make makeup very hard to do right, it would be fun to add scars during the game, like seeing our character becaming more and more rugged while advancing on missions.