Nubie - 2 Pics doing the same thing

I am using a 16f877 to control some relays via pushbuttons for my pool equipment. The pushbuttons have LEDs that work when the relays are on. It works well but I would like to
add another location with pushbuttons approx 100 foot away. Can I connect 2 (or 3) 16f877s
with a serial connection or I2C to accomplish this? Or should I try using a port extender?
Any help would be appreciated.

Thanks in Advance

If you're using the hardware USART with MAX232 type drivers on your network, and good quality CAT5 twisted pair wiring, you might be able to get it working at this distance, but nothing beats moving to RS485 for reliability at distances > 25'.