I would start by telling your pastor that you support him in leading the church, just as God expects him to. If he asks what you mean, tell him that he is compitant enough not to need the instruction of Rick Warren. He is YOUR pastor, Warren isn't. God placed HIM in YOUR pulpit, not Warren. Also, I would let him know that you are interested in a mini-series of expository preaching.
http://www.9marks.org has a great writeup about that, including the why's, how's and all the other facts.
Our church has, just this year, moved from topical to expository preaching, and I can say that the sermons are more powerful when the word of God leads the pastor's sermons, rather than the pastor picking and choosing verses that he likes to support his points.
But to summarize my advice for you, I'd reassure the pastor that you are confidant that the Lord can lead him toward a preaching style and a method of preaching that God desires for His church. The PDL movement is all about the numbers, and many pastors look at the attendence or the collection to determine their success. However, the Bible says that the way is narrow and tells us that the love of money is the root of all evil.
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...all Christians should stand up and tell it like they see it. Let the chips fall where they will. Don't worry if the public doesn't even agree with your most basic assumptions. Your job is not to win. Your job is not to control this society. Your job is to say what God wants said." - John Piper