Had a off the record talk with my manager, told him I was interviewing and expected to render my resignation by end of this month, gave him a 3 weeks head up. He said he understood and would try to retain me. Well he did, I was Going to resign this Wes, cleaned off my computers etc.... Today he sat down with the Director level and give me a VP signed letter, a 35% raise, a title increase plus a three year stay bonus. My manager has always been decent, he is in a tough spot but ended up retaining me.
PS treat your manager as a human, respect and straight up....it works.