12 Characters
As long as you're using WPA or better still WPA2, with a network key 12 characters long containing upper-case, lower-case, numbers and special characters, you're safe. A key of this length is totally uncrackable by most people/groups and would take much more than a lifetime to crack even with access to a supercomputer array. There's absolutely no need for an unwieldy key of 20+ characters, let alone 63!
The problem is that many ISPs don't give out very secure keys. For example (but by no means limited to) Sky. Their old G routers had SSIDs that started with SKY, and provided network keys of 8 upper-case alphas. Anyone seeing a network named SKYxxxxx, would then know that its network key is made up of 8 upper-case alphas, thus making it relatively easy to crack. Not very many people know they can log into their router's config, let alone how to change their network key! I can see several Sky networks in my neighbourhood, all of which are using older G routers with WPA security, the owners of which haven't switched to WPA2 since new firmware was released last year allowing this superior protocol.
Powernumpty, shhhhhhh about channel 13 !!