Which communication method to choose?

I am Building a project which requires communication between two Arduinos and I'm having a problem choosing the method. I was going to use I2C because of the two wire system but i need the information to travel over 200ft of cable. Is there a different way that uses few wires or any type of booster for the I2C to travel further?

There are boosters for I2C, the PCA9525 for example. But I've never really seen a definitive answer to exactly how long a cable these can be used with. Possibly because it depends on capacitance and that's different for all cables.

OTOH RS-485 is well documented to be good for up to 4000' (1200m). RS-485 will use the same number of wires but does need a UART or at least SoftSerial.

EDIT: Have a look for SMBus, that's an industrial bus based on I2C.