I've Planet Busted countless worlds. Simply because, get this, I knew I would never have the time to come back and settle that stretch of space.
So my Spore games tended to start out like this.
First. I secured the area of space around my Home world, making it pretty much a stronghold of deceit and allies bickering with each other, keeping them off my back while I systematically, casually destroy everyone around me one at a time. Then when I'm relatively safe, I take the first Black Hole next to me, and end up in at the other side of the universe. I use this opprotunity, and usually end up where there's only a few small, defenseless empires, that aren't much harm at all, and BRUTALLY sweep up as much land as possible there, as much as I can micro-manage without being annoyed.
I'll even waste Anti-Matter bombs by the dozens, killing Tribal world villages one by one, just for the pretty lights. And countless civilized worlds the same way, in fact, MOSTLY the civilized staged worlds, because its at the highest Terra-level. Actually, around the time I stopped playing Spore, I would plant one of those Monoliths on Tribal staged worlds around the mentioned 'CONQUER EVERYTHING ZONE', wait for them to bump to Civilized or a few out of hand small empires, and brutally crush them in a barrage of Anti-Matter warfare.
And usually, I would wrap this up by targeting all of the surrounding Empire's home planets, and lighting off a Planet Buster for celebration fireworks.
Actually. I don't ever remember thinking ONCE there was a Diplomatic option. It was either Anti-Matter nuke-a-thon, Blue Spice worlds grab and then throw a little money at them to get rid of war status, or full blown Planet Busting (I usually had as many PB as I possibly could by the end game) as many enemy worlds as I could.
I would then finish playing that race, by embarking on a MAD, INSANE, DERANGED War on the Grox, and EVERY hostile race that game in my path. I would go In a straight line spanning around, 10-20 stars, destroying everything. This took hours, but I would eventually get to the center of the universe after blowing up probably hundreds of planets. Its just not freaking possible for me to embark on a galaxy-wide war. I would just switch to a new race upon getting to the center, as wasting my time wiping out the Grox with another few thousand more Planet Busters was a waste of my time. The initial war with them, the genocidal intent I always had at everyone in my way...
Spore makes it pretty easy to throw around Death Star level weapons. To bad it wasn't as good as it was suppose to be. Excuse me while I give Defcon a try.