Becky over at the Netflix Fan Blog shares her trick for getting her first choice from her queue every time.
There are several not-yet-released movies in my queue that Netflix has given a release date. I keep one in my #1 slot almost continuously. Because it hasn't been released, it gets passed over every time. Meanwhile, Netflix is fooled into thinking I never get my first choice. Since they allocate discs based on who has been getting their first choice most often, then they always give me my "second choice", which is my real first choice.