1)"I`ve expected you for a long time."
2) "I`ve been expecting you for a long time"?
Both are grammatically correct, but they fit better in different situations.
If you were waiting for me to come to your house, and I am very late, use 2). 2), through the use of 'been', is passive. You passively waited for me to come. I say, "Sorry, the traffic was terrible."
If I am a killer, and you are hiding from me in an anonymous village in rural Japan, then one day I knock at your door, use 1). 1) is more active, you were actively thinking, and expecting, I would find you one day. I say, "You knew I would find you in the end." Bang bang!!