The best way to see the most stations is to view the whole country and use the TimeLord feature to go back an hour. That will show all of the observed temps. It looks like this: http://wxug.us/p535
Stations are as reliable as the station owner's internet connection. If someone looses power or internet, the station goes down. Other than that, stations should stay available and reliable. We have quality assurance code running to keep bad stations from reporting current conditions in the API and on our site.