hm...my current game would be much better if I'd had a good RNG.
I took out Cyrus in 2100BC, but should have taken him out in 3200BC when I attacked Persepolis with 3 warriors when he had a single warrior defending. Unfortunately, I lost and ended up just barricading him until I had some jaguars.
I'm playing with 10 opponents as well, and just finished taking out the 5 AIs in the south, and starting to vassalize the AIs in the north. I plan to vassalize all but one, the most advanced, and then start settling the deserts. I didn't build my first settler until 1000AD...no need, since I was constantly at war with Cyrus/Hannibal/Vicky/Napoleon/Ragnar?Augustus until then. I built my settlers then to fill in some good city sites that I hadn't let the southern AIs get to before killing them off. Off the southern AIs, only Ragnar was able to build more than 3 cities, and Napoleon was the only other one ever able to have 3 cities at once.
Ragnar vassalized around 500AD, and I gifted him CS and Machinery immediately so I could have his zerks helping me take down Augustus...took 2 of his cities, razed one, and then he vassalized. Right now I'm trying to get Alex to vassalize to me, I've taken and razed 3 cities, kept 1, and Caesar has taken 1 of his former cities back from Alex.
I think it would definitely be easiest and fastest to attempt to take out all but a couple AI and then spam settlers...I just had bad RNG

On the plus side, I was able to take out all the AI up until Caesar with Jags, and up to Ragnar without Cats.
Harbourboy, if you decide to try again, perhaps try it with 10 opponents...not only does it mean the AI have less land each to spread to, making them weaker individually, but it also lowers the domination limit to 56%, which is the main reason I went with 10 opponents.