I have a similar tactic as Turul's, except I have more armies and corps. I utilize Lt. Generals in stacks of 3 (brigaded with L or M armor, L artillery, and engineers 1-1-1), I also have stacks of 5 for generals using similar structure where I double up on the art. and armor, and finally stacks of 7 or more for my field marshalls where I tripple up on the same basic theme with perhaps a specialized division or two like mountain or marines, depending on the type of terrain in which I will be deploying that particular army.
I also use a few armies to create a defensive army corp (using 2 generals with stacks of 9, and 3 or 4 Lt. generals with stacks of 3, all with almost exclusively heavy art. and AA) to secure the flanks and hold key positions while the rest of my army attacks and encircles. Then I strategically place a few garrisons with MPs to help reduce partisan activity and decrease revolt risk/increase ESE.
Lastly, I use around 5 or 6 panzer armies to encircle, capture key provinces and airfields, and to exploit opportunities where speed and overwhelming power are needed. These armies usually consist of 2 generals or field marshalls with up to 9 armored/mechanized/motorized and all brigaded divisions, and 3 or 4 Lt. generals or generals with up to 4 or 5 armored/mechanized with all brigaded divisions. My panzer divisions only have brigades which do not decrease their speed, so any brigade that confers bonuses to attack or defense, but that does not slow my panzer armies down at all is fair game.
My HQs (usually 4 or 5 at most) stay just behind, next to, or in the same provinces as my main forces that I am attacking with, but I rarely ever directly include them in my offensives (for reasons I stated in my post above). I always like to have them very close by to my main forces as they do confer several useful and important benefits, plus, in a pinch, they can hold off several brigaded divisions for days at a time when defending while losing very little org or strength.
As for the airforce, by Barbrossa I usually have 24 interceptors organized into six airforces. At least 3 of these constantly patroll the English Channel to keep allied bombers at bay, while the remainder remind the Soviets who is in control of the skies over the eastern front. I also use 2 airforces of tac bombers (w/ escort fighters attached) of 4 tacs each, and 2 airforces of cas bombers with 4 cas each to punish the soviets and soften them up where necessary. Usually I will also build at least one airforce (again, with 4 wings) of naval bombers to support my navy/bomb convoys. And I am not above using half or more of my minor allies (Hungary, Romania, and Bulgaria) airforces to cover western Europe in case any Allied planes do manage to break through my net of interceptors over the English Channel. (I also use parts of their armies to garrison the coast of France, Belgium, and the Netherlands).
So far, this overall approach has proven to be highly effiicient and very effective. I have experimented with more than a dozen different approaches over the last 6 years, and this one seems to me to be the best yet. But I am always open to new ideas and strategies. That is why I love these types of threads the best. I get to learn so much and benefit from the minds and experience of other great players and lovers of strategy. It just doesn't get any better than that!