I recently completed a massive built where I developed a series of blueprints I called "bricks". These were standard builds that allowed me to easily construct almost anything that could be made with an assembler or created in a furnace. I developed some very standard bricks that can be used for almost anything, plus some more specialized ones for different scenarios. This is a blueprint book that contains all my brick blueprints that I used there. Just drop down the blueprint that fits, assign the assemblers to the right recipe, set the requester chests and watch it go.
These tile very well - Just drop one down and lay another right next to it, overlapping the common edge beacons and power.
No guarantees that it is 100% perfect or absolutely optimized, but they work great for me.
Assumes full 'bots (sorry belters!). You're going to need a lot of roboports, especially for the higher-throughput items like green circuits, wires, etc.