So I've played the game a few times and have a couple suggestions from a beginner's point of view.
First why are the wars 8 days? Personally 6 days would be perfect. I have a few friends that we play together and it works best for us to start a battlefield on Friday night. If the war lasted 6 days, we could then take a day to regroup basically and then start the next battlefield on the next Friday night.
LC troops. Obviously I'm a beginner and don't know all the ins and outs of the game yet, but LC troops are way overpowering for the few people that aren't in a strong league. I can understand that they should be better than normal troops or cheaper or something as a benefit, but so far they seem DRASTICALLY more powerful. Transport planes that can carry tanks are one example. I would think that maybe make a new transport plane that you can make in your own munitions factory. Maybe it can have a capacity of 16 and be available at munitions factory 10 or something. So it isn't quite as good as the LC transport plane, but it is still available.
Battlefield promotions. It took us like 3 battles to figure out why we couldn't do in battle diplomacy with other leagues. Anyone above member in the league should be set automatically to a staff officer in the battlefield.
That's all I have so far.