What is the length of the songs?

This depends on the occasion and the amount of detail you want to include in the song:

Our favorite option is a two to three and a half minute song

They contain about 15-30 lines of lyrics, (1-2 verses).

They contain 1-2 verses (or a verse and a transition) and a repeated chorus; about 100-200 words in total.

They have enough space in the lyrics to capture memories, future dreams/plans, or to tell a dynamic story.

Give the song time to rise and fall emotionally – just like a story or a movie. For this reason, most popular music stays around the three-minute mark.