In my opinion as a native English speaker we don't particularly use to long for very often. The distinct difference in my opinion would be that to long for is usually someone you love romantically. "I miss my mom and my dad" "I long for the day that my love returns to me"

"Missing" someone means you are upset that they are gone. To "long for" someone is to want them. This could be because you miss them; however, it can also mean that you want someone to love you, even if you know them and see them every day. I hope this helped.

Oxford Dictionary's definitions for the word "miss" is to "notice or feel the loss or absence of". long for Web definitions: to have a desire for; to yearn for; to crave for; to miss someone http://en.wiktionary.org/wiki/long_for