If I've learned one thing from playing FOG, its the value of an Inspired commander. Sure, they cost a lot in points (80 compared to 50 for a Field Commander) but the extra edge they give you makes it worthwhile paying the extra points.
Take Hannibal (above) for example. This bad boy gives you +2 on the Initiative roll at the start of the battle - meaning that your opponent will usually have to lay out his BG's before you do. Then simply line up the troops with your POA's in mind (e.g. line up your elephants against his cavalry or swordsmen) and you're already on your way to victory.
But it doesn't stop there. He adds +1 to all CMT tests within 12" of his position (provided he is in line of command) - which can make a big difference to your troop movements.
Attach him to a Battle Group though and you get a whopping +2 on a CMT roll - enough to get Gauls marching in step and contracting and expanding like an accordion!
The Inspired Commander also makes his presence felt in Cohesion tests. Place him in the centre of your battle line and watch him him influence Cohesion Tests with +2 on the roll (so a failed '6' becomes a passed '8'). Time and again I've seen Hannibal work wonders on the Carthaginian morale as my Republican Romans have chopped them to bits but rarely have they dropped cohesion levels with Hannibal behind them.
If a valuable BG goes Broken, you can attach him (if you dare) and get +2 on the Cohesion Test to stop the rout and (hopefully) get them from Fragmented to Dirsrupted to Steady - but this means he won't be around to influence anything else for a bit. But having such a wide (12") influence means you can afford to attach another Commander to a Broken unit and have your IC use his influence to cover for the other commanders' absence.
So if you can - and if your army list permits it - try an Inspired Commander on for size. You won't regret it!