In thinking of how poorly the WWE does feuds today, I was watching the Bossman/Heenan feud and it was such a great midcard feud.  

1.  Easily identifiable issue:  Heenan insults his mother

2.  Way to stretch out feud:  The Heenan Family culminating with the match against Mr perfect that he should have won

3.  Heenan by being the focus but not wrestling let’s you do all sorts of things with it sort of like the McMahon/Austin feud.   

Yeah, it's just too bad they couldn't stick the landing, but Bret Hart was the long game for Mr. Perfect anyway.  Plus Rude leaving of course screwed it up.  Still, simple and effective.