After you've been through a few wars you develop an appreciation for defense troops, how they handle themselves and how many it takes to stay off an attacker. Whether your goal is to completely annihilate your attacker's Offensive supply or just dodge and snipe a cap attempt, having nearby troops by the thousand can be a city saver.
This setup is where you grow defense troops in every city. Yes, I know how that sounds, but hear me out. If you grow 3k lancers and 1000 guards (and/or 4k sentries) in each city, you can mount a seriously decent defense for when you are attacked. Guardians are awesome for a quick response all purpose defense troop. If you have 5K guardians in your city, coupled with 200 - 300 RAMS (yes rams as a defense troop, who'd have thought) and your wall is 25, it will take several cities of bombardment to clear your city. The rams actually fortify the wall bonus and kill off any rams or ballistas they may send at you. Now guards, they move quick, they defend hard and are great for a first line import. However, do not underestimate the power of lancers and sentries! These guys take little time, resources and farm space to train, even though they walk a little slower, they are definitely worth the effort.
So back to design, if you have 3K lancers, 3 - 4K sentries (that's 6000 farm space) and 1k guards (another 4000 farm space) that's 10k farm space, in a maxed city, which is anywhere from 3k to 4k of farm used by buildings, you still have 9 - 10k left for attack troops! When you are attacking it will certainly take you longer to clear a city, but you can rest assured that your kingdom is safe.
It wouldn't hurt to have a NUKE city in the midst of your cluster of Defense forward cities. A city that has strictly attack troops can be a quick and easy way to crush a man's soul.. I mean city... In the same breath, having a strictly Def city within your cluster is also smart. Nothing like an extra 8000 lancers within 3 hours of your scholar cluster to make a guy sleep better.
Scholar cities, when setting up Defense Posturing kingdom design, you want to grow your scholars and adequately support each scholar wave, bundle three cities, all within a 6 block radius of one another (the closer the better - especially if math isn't your strong suit) in each city you grow 2 scholar waves. When actively warring, you want to support each scholar wave as if it were going to be sniped, the more troops the better!!! If your cities are close by, you can always use those three to set up scholar trains, they will land within a reasonable amount of time and you will cap your target. It is always better to send more scholar waves then you think you'll need, you may cap, then recap, but at least YOU have the city, not your victim, and you can always retrain your scholars.