Prays with Praise
From: H. in Philadelphia, PA
If G-d is so great, why does He need us to praise Him so much in our prayers?
He doesnt. We do.
Regarding prayers and our relationship to G-d, the commentaries discuss your question at great length. Most explain that the purpose of prayer is not for the benefit of G-d but for the benefit of the person praying.
Here are two relevant quotations, and then I will comment.
Maimonides teaches that "It is a positive commandment to pray every day, as it is written, You shall serve the Lord Your G-d with all your heart. The eighteen blessings are divided into three sections: the first three are praise to G-d, the last three are thanksgiving, and the middle blessings are requests which are major categories for all the needs of the individual and the community..." (Mishne Torah, Laws of Prayer 1:1,4)
The Talmud instructs us that "One should always arrange the praise of G-d first, and only afterwards pray." (Babylonian Talmud, Berachot 32a)
In prayer, we first of all state to ourselves to whom we are praying, and to whom we are relating so that we should have no misconceptions and think that we are "changing G-d's mind". This section of prayer is called "Praise".
In the second stage we then reflect upon our dependence on G-d for everything. We reflect upon the uses of the tools that G-d gives us. This stage is called "Requests".
Finally, we express our appreciation that we are happier people, and instilled with humility and gratitude. This final step is called "Thanksgiving".
G-d does not "need" any of the above; rather, it is we who need it. As we pray, we are therefore changing ourselves to some degree (if we do it properly). Being changed means that a new and different Divine providence applies to us after the prayer. On the highest levels, prayer allows a person to reach spiritual heights close to prophecy as the Code of Jewish Law states: "One who prays must think in his heart of the meaning of the words that he says with his lips. He must imagine that he is standing before the Shechina (Divine Presence), and he must remove all thoughts that may bother him until his thoughts and intent are purely [involved] in prayer... the pious Sages of antiquity would meditate and focus on the prayers until they would divest themselves of their physicality, and their intellect would completely overpower [all other aspects of the self], and they would come close to the prophetic level..." (Orach Chaim, 98:1)
May all our prayers be answered in the way we would like (if we ask for what is in truth good for us!).
Of course, perhaps the most important message to keep in mind when praying is that G-d understands what we truly need a lot better than we do! There is a very thought-provoking story that amplifies the idea.
Someone once came to Rabbi Kahanaman (the late Rosh Yeshiva of Ponevizch and one of the driving forces behind the revival of Torah in Eretz Yisrael after the Second World War) to complain that he prays to G-d but G-d doesn't answer.
The Ponevizcher Rav answered "G-d does answer. The answer is No!"
Or, as the Chofetz Chaim put it, "Be careful what you pray for...you may get it!"