We know of the Annunciation from Luke, as well as the conception of John the Baptist, the Visitation, the Birth of Jesus, the visit of the shepherds, the Presentation in the Temple, and the Finding in the Temple; all from Luke. He also gave us the great songs of the New Testament that are prayed every day in the Liturgy of the Hours: the Canticle of Zachariah in Morning Prayer, the Magnificat of Mary in Evening Prayer, and the Canticle of Simeon in Night Prayer.
The Gospel of Luke has great value as literature, but even greater value as the Word of the Lord. With Mary we can sing, "My soul proclaims the greatness of the Lord, my spirit rejoices in God, my savior."