Having the same problem over here (iPhone 6). Every so often wifi does not show any networks when many are available. Reboot fixes the problem.
Anyone know if 8.0.2. has fixed this? I was waiting to get some feedback before doing the update.
Had this happen twice on my 6 plus now - WiFi signal dropped at home whilst on the 5G network & searching, no available networks in WiFi list (normally at least 8) yet, my old iPhone 4 running on the N network has a full signal. Re-booted phone & problem solved - easy fix but, annoying all the same.
Both occasions have occurred since I upgraded to IOS 8.02. My Wife upgraded to IOS 8.02 within the same hour & thus far, her iPhone 6 plus has not suffered this issue.