Since NOTA relies more on tactics and strategy than many other mods, I think adding better formation support would be excellent, if it's possible. I'd propose a couple things:
An option for the entire selected army to move at the speed of the slowest unit to keep the army from falling apart. Arty and other slow units always lag behind the main army and sometimes by the time they get to the battle, the main army is already defeated.
Some sort of option to choose how many ranks deep the army is. Having a long thin line isn't always the best solution since it's easy to break through. Furthermore, the option to have the army auto-form the ranks, so that shorter range units fill the front rank and longer ranged units fill up the back while AA units take the very back (let's face it, most of the time you don't want your AA just uselessly walking around the front lines getting shot at).
Right now, the best we can do is use the formation widget to kind of snake around to form ranks, but the units kind of arbitrarily fill the area. Sure, you can individually select each unit and draw its own line, but it's pretty inconvenient when in the heat of battle.
Like I said before, I have no idea is this is feasible or possible. Just throwing it out there.