Google Flight Search
It is very easy to get flight-related information from within Google Search. All you have to do is enter the applicable information that you would ask a Customer Service Agent at any major airline over the phone.
Type in, for example, "flight time Miami to San Francisco". Google returns results showing the answer to your question/inquiry as well as actual flights you can take that fall within the domain of your search parameters, which are, in this case, the cities of Miami, Florida and San Francisco, CA.
All The Best,