If you happen to own an iPad or iPhone, I use it for a quick and dirty "Wifi survey". Apple's AirPort Utility" app (free) has a :Wifi Scanner" capability if you enable it in the Settings. In Settings, look for "Air Port Utility", and turn on the button labeled "Wifi Scanner".
Go near your PC, open the AirPort utility, and you'll now see a "Wifi Scan" label on the top right. Tap that, then tap "Scan".
Let it go for a good 30 seconds, then tap "Stop". The list of wifi networks is sorted by relative signal strength, and it shows the wifi channel used by each one. As a "bonus", tap the "(i)" icon at the bottom of the list. You now have a neat summary of which wifi channels are in use, and how many networks are using each channel.
I use this to de-conflict my wifi from time to time and it has proven very useful. Best of all, the app is free (assuming you have an iPad or iPhone).