How precious to me are your thoughts, O God!
How vast is the sum of them!
If I would count them, they are more than the sand.
I awake, and I am still with you.(ESV)
Saying that God's thoughts are precious is a two fold statement.
First, it is a statement of reality. For David, God's thoughts had become precious becaus he was beginning to understand what God was thinking about.
Second, it is a statement of theory. God's thoughts should be precious to us. We should begin to put a high priority on what God is thinking about us. So, we begin to think of God's thoughts the way we should, which will lead us to a better understanding of reality.