• The main idea of Kings (1+2) is that Israel's kings were an abject failure, leadings to a divided kingdom and final exile due to sin and the rejection of God, despite repeated warnings.
• Approaching death, King David anoints Solomon, who starts well but then marries foreign wives and worships foreign gods.
• After his death the norther kingdom (Israel) and southern (Judah) are separated, with both descending into idolatory, although Judah occasionally has a good king (e.g. Jehoshapat); Israel does not and increasingly resembles other nations.
• Elijah and Elijah are zealous for God and perform a lot of miracles.
• Much detail is given about the temple and it is plundered by its own leaders and foreigners.
• Prophets tried to counter bad kings.
  
• The legacy of David ensures that at least one tribe surives.
  
• Despite being nearly destroyed and in exile Jesus will descend from David's lineage.

Reference: www.patsieler.com/books-of-1-2-kings-summary.