I have a Macbook Pro Retina, 15in, and I have the above issue. In a related question (Wifi doesn't work unless I turn it off then on again) a user commented:
For as long as I can remember, I've had to do this on my MacBook Pro Retina 15″ — I've always presumed it's the router, as I only have the problem at home. I even have a script that will automatically cycle the Wi-Fi if it's attempting to connect to my home network and fails for more than 3 seconds :) – grgarside Jan 26 at 20:00
Does anyone know how to write/load this kind of script? Thanks!