If anybody is still looking....the free wifi man is simple and does everything most folks need, including live ping times and speed tests. UBNT knows networking...so this should be a safe bet to stay up to date, and possibly get more features or improvements.
Pretty sure satcomer is referring to the wifi icon on the toolbar on a Mac. You mentioned iOS...so while the option trick works, to see the details of a wifi connection on a Mac, it is not the platform you mentioned.
After doing some testing, I have to agree, that wifi sweetspots looks pretty promising for finding...well, sweet spots. It really depends on what you want to view/monitor though. wifi man is pretty solid to map out devices and check their particulars.
If your network is already using one of the recommended channels or if simply all channels are saturated, then WiFi Signal will not offer any recommendations. Make sure channel recommendations are enabled.
www.intuitibits.com
It is a menu bar application that will show your current Wi-Fi status.