We have talked about the ways in which various viewpoints differ in the interpretation of Genesis 1. However, Genesis has some clear messages that don't depend on how we view the days of creation. The following statement was taken from the book Authentic Christianity: From the Writings of John Stott, p. 89, InterVarsity Press.
God's Word is designed to make us Christians, not scientists, and to lead us to eternal life through faith in Jesus Christ. It was not God's intention to reveal in Scripture what human beings could discover by their own investigations and experiments. So the first three chapters of Genesis reveal in particular four spiritual truths which could never be discovered by the scientific method. First, that God made everything. Secondly, that he made it out of nothing. There was no original raw material as eternal as himself on which he could work. Thirdly, that he made man male and female in his own image. Fourthly, that everything which he made was “very good”. When it left his hand it was perfect. Sin and suffering were foreign invasions into his lovely world, and spoiled it.
The young-earth creationists J. Ligon Duncan III and David W. Hall present some similar points in the book The Genesis Debate: 
- God created the world and is distinct from it (but not unconcerned about it).
- God shaped his creation from formlessness into order and filled it from emptiness to fullness.
- God's world was originally good and, therefore, different from the corrupted world in which we now live.
- Man's sin is entirely responsible for corrupting original creation.
- God's character (justice and mercy) is revealed as He responds to the three “low points” of primeval history: the Fall, the Flood, and Babel.
Certainly ‘Creation by God’ is an important Christian doctrine. The fact that man was created in God's image provides a sense of dignity to all men. Also, the fact that God's original creation was declared to be ‘very good’ is what make man's Fall into sin so tragic. Our sinfulness is not just the way we are, but is a corruption of what we were meant to be.
I hope that you can see from the above that, as Christians, we can agree on many important aspects of creation while possibly holding differing views on the length of the days.