I don't see any reason to sign peace with either Portugal or France. We want their territory, and we get War Happiness from our wars with them (although of course we have to make sure our troops aren't in enemy territory too long, otherwise War Wearniness cancels out the War Happiness). One or two more turnchats should finish them off.
China we can probably eliminate in one turn; it's just a matter of getting the troops lined up. We've been short on troops and long on enemies, so they haven't been a priority.
I still favor annexing Persia, although we'll want to keep an eye on how we're progressing towards the domination limit. Unless they attack us (always a possibility), I'd wait to take them on until we're finished with Portugal and France.
BTW, in the future we may want to pick a few short wars with the civs on the far continent. The idea would be to send troops in to raze and pillage in order to slow the progress of those civs. Maya's capital is accumulating a lot of culture, although I don't think they'll threaten to achieve a 20,000 point single-city cultural victory. Still, we may want to target that city for razing at some point.