So, right now we have two options for keeping hostile mobs from spawning in our base.
1. Build underground
2. Place lights in every nook and cranny a mob could possibly spawn in, then hope for the best.
Now, I like to build above ground. Despite my well fortified city walls, I'm plagued by monsters popping out of alleys and rooftops, usually blowing me up as I'm putting finishing touches on something important like a nuclear reactor or MFSU. Since wiring luminators everywhere is problematic, I end up using torches and stone-aging up my industrial civilization.
My suggestion is a spawn blocking machine. A fairly expensive machine that draws a steady supply of power to block all mobs from spawning within a reasonable area.
An example recipe:
Slime Balls = Ender Pearls (They control teleportation of mobs, right?)
Example EU Consumption:
10 Eu/t to disable spawning for 20 blocks in every direction.
So...pretty expensive, but not unbearably so. You could afford to place them around your base, but, you probably won't want to line mine shafts with them or anything and you'll still need to build walls to keep mobs from walking in.