We know more about the sending out of the 12, than of the 72.
Jesus warns cities that reject Him and the 72: it will be worse for you than other Gentile cities that weren't as exposed to Him. He even compares His adopted home town of Capernaum with Babylon (compare Luke 10:15 with Isaiah 14:13-15).
Jesus warns the 72 not to sensationalize their power over demons. He saw Satan fall from heaven, like lightning. Far more important to give thanks for your salvation, than for your power over evil.
Jesus is delighted with His Father's plan to reveal Himself to the simple, not the wise. A scribe asks about the Father's revealed, moral will for us: love your neighbor, as even Samaritans do sometimes.
Pray for God's name to be remain regarded as holy; for His Kingdom to come to earth as His will is done in heaven; for our provision, forgiveness, mercy and purity. Pray persistently, to a Father who delights to give.
Israel was to be a light to the Gentiles, as Jonah and Solomon were; don't hide it under a basket.
The Pharisees don't handle the Word well, loading people with rules on minor things while ignoring the big issues. This is connected with their rejection of Jesus, which will lead to the judgment of all past generations in this generation. Jesus intentionally made enemies with these shepherds, because they were wrong and were hurting the sheep.
Jesus prefers to speak of His works and mission from His Father, instead of using the words Messiah and Christ. Though the two are synonymous theologically, the political connotation was disruptive of Jesus' earthly ministry. They accuse Him of blasphemy; He points to His works to prove what He says is true.