To me, it would be great if in the future one could give precises instructions (itinary) to fix the path that a corps should follow until it will finally deploy. That, without the need of indicating intermediates times to the AI if not necessary. The AI will just do its best to reach the final position accordingly to the player wishes (of course with penalties if the choosen path is too demanding for the troops). It would add a lot's of adrenaline to the game : it might be harder to stop the movement and the risk or bad surprise would be higher than if you progress carefully by little jumps. On the order hand the game might be more enjoyable, with less writing orders to adjust the itinary. Could be very appreciated in campain mode.
It would be also great if one could give combined orders to detached units, group of units or even corps: for instance if you see that there is a gap that opens up in the opponent line, give to cavalry units order to fill it and THEN attack the ennemy on the flanc ASAP !!!. At the moment I think that the only way to do so is to give a march or deploy order to a destination and then another order with another execution time to attack (for one unit) or deploy (for a corps). Since it is hard to estimate the time it will take to deploy (for a corps), the time given to order attack might be too early (the corps is not deployed yet) or too late (the "surprise" effect will be lost!). It would be better to let the AI do the job: just by giving it the path to follow and the order to be executed when the destination will be reached (attack left, right, in front; hold the position; arrass enemy...).
It would be also nice if one could easilly detach a group of units (let's say a cavalry brigade) from a corps for special missions without to assign a new corps commander to it taken from the pool of free commanders that you have saved (just using the general already in charge). But I think that this is already planed, with a brigade or division AI)
I know that it is allowed to especially "motivate" one unit before the beginning of the battle to support the tactical plan. But it would be great if, during the battle, the commander in chief would be allowed to give only one "special order" based on standards historicals orders such as : "hold at any price", "full assault", "reach this position as fast as possible"...
And... if in the future we could reach a 1/5 scale for the game it would be great : that would narrow the intervals between the units and give a more impressive sensation of mass.
But these are just wishes, the game is already a masterpiece as it is now compared to what exists.
Congratulations !