Expand the main quests, probably with meaningful sidequests and easy-to-access background information (not scattered notes under tables and chairs) about the events and the major characters (most of the mage-templar war and orlesian civil war is detailed in novels, and the game should not rely on these to present us a storyline).
War table overhaul - much more of these quests should have a playable part, it would surely help to fill those vast empty areas and connect the redundant, optional ones more to the main story.
More involvement from the villains - in Origins we were shown quite often what Loghain is currently up to, in DA2 Meredith and Orsino were also in the middle of everyting that has happened in the game. I'd love to see more Corypheus-Calpernia/Samson scenes.
More cinematic dialogue - it may seem like a small or unnecesarry addition, but the varying camera angles, gestures, etc. make the conversations so much more natural and overall better.
Fort overhaul - taking over forts from bandits and blood mages should be a more large-scale confrontation, with some planning and troop positioning involved (maybe and RTS-like minigame?), instead of 4 dudes bashing in the castle door and killing everyone, working their way up to the commander. Also, fort customization as it was promised in the alpha - forts for garrison troops, or spies or providing shelter for traveling merchants.
More visible Inquistion presence - random encounters, where soldiers are fighting bandits, beasts, demons, helping refugees, building/renovating structures etc.
More larger cities and an expanded Val Royeaux.
An option to be a dividing figure/tyrant/religious fanatic.
Tac cam fixes, so it no longer has to take the stairs to reach elevated postions.