It is my first Always at War ever so my thoughts are not exactly based on experience but on reasoning.
First of all it is key to decide if we want a run on Monarchy or the The Great Library. There are no shared techs in the path to both. Although we don't have Alpha TGL should be possible if we can get Philo first. Much cheaper to research compared to Lit. and we can choose Lit. as free tech.
TGL is a timecritical goal, the other ones are less time critical, i.e. we could research Warrior Code or IW before heading to Monarchy.
With respect to walls and cats I usually prefer and approach of keeping the AI out of our terrain and in that approach walls are basically useless because if everything goes well the AI should never reach our cities. Based on that I have a preference for PP's approach but as said that is based on reasoning, less on experience.
One observation from the previous SG, PP and me more or less have the same approach to warmonging so that could explain my pref. in this game.
I certainly plan to play a couple of testruns.