Siam and Greece manage the city-states(and everything else) differently, because Siam gets the increased food/culture/faith while Greece is better at maintaining more allies. They're also broken with Papal Primacy + the Patronage opener because their influence will never freaking decay; incidentally that's why I think Papal Primacy should be reworked, it's either very very abusive or not useful at all.
Also, I would certainly not put the Companion Cav over Siam's UU(Stampy). Stampy has a whopping 25 strength at a point in the game where the whole things that can stand up to them are Pikes/Muskets/fortified Longswords, not to mention the +50% bonus vs mounted to just crush other Knights. It's more defensive than offensive(although it can do that okay too), and it's a real monster on defense. Unless you're playing a civ that matches up very well(Spain in particular is awesome) you're in for some pain, especially if the AI grabbed something like Himeji Castle.