First I'm concentrating on all my lights and fans. I plan on having my Mega set up to be a server so I can control the system using my phone or computer. I'm also planing on having several nanos set up throughout the house to flip relays for all the lights and fans. I'm trying to figure out home my arduinos will communicate with each. For now I just need the nanos to tell the server what lights are on or off. And for the server to be able to command the nanos to flip the lights on or off.
So i've thought about using I2C, ethernet, wireless, or rs485.
I2c is not reliable for the distances i want to run, ethernet seems expensive, ands wireless is expensive and also might not be as reliable.
So as of right now rs485 seems the be the best bet. Im sure there are other things that im not thinking about. I would like some input before i buy any more parts