Stumbled across this great article by Mario Ciabarra with some quick fixes for the Wi-Fi issues plaguing so many of my clients.
I don't recommend giving this out to just everyone though, because it requires a jailbreak for the iOS fix and a terminal command for Yosemite. Keep this one power users only.
It's really great insight into what is going on, but I'm surprised that Apple would tank the Wi-Fi interface so bad. I'm hoping for a fix soon.