You can find a YouTube playlist here with many of the songs suggested below.
Gathering
For me it wouldn't be Advent if you didn't begin with O come, O come Emmanuel (CH 273 / MP 493). The simplicity of the plainchant melody has allowed people to experiment with it in many different styles and it can even work very well unaccompanied. If you are looking for some inspiration or a video to use in an online service then try Enya, Pentatonix, Punch Brothers, Sufjan Stevens, or Lincoln Brewster. Some other options which could set the tone for the season well and pick up on some of the general themes in the readings are Hear, O Israel (Getty / CCLI) which could be used as a call to worship, All who are thirsty (MP 1025 / CCLI), and Come, thou long-expected Jesus (CH 472 / MP 102).
If you are using an Advent candle lighting song then Christmas is coming (CH 282 / CP 34) and Advent candles tell their story (STF 165 / link) are good options for the pattern of Hope, the Prophets, John the Baptist, and the Virgin Mary, while Hope is a candle, once lit by the prophets (CH 284) and We are a people of hope (Hope) work well for the Hope, Peace, Love, Joy themes.
Word
You might like to use a short Advent song before the reading of scripture. This is a good opportunity to give some musical continuity to the season, either by using the same song each week or by using songs in a similar style. The following songs all have a similar text, praying for Jesus to come, but use a mix of English, Latin and Aramaic: Maranatha (MV 19), Come, come Emmanuel (link), Veni, veni (WGRG), and Veni Immanuel (WGRG). There are also some settings of plainchant which can work well here as continuity through the season, with the simplicity of the music allowing an opportunity for the power of the words to really sink in. The Advent Prose (NEH 501) is widely sung throughout Advent while O heavenly Word of God on high (NEH 2) would be another option.
CH4 has two excellent contrasting options for the psalm with Pray that Jerusalem may have (CH 82) from the Scottish Psalter and I rejoiced when I heard them say (CH 83) which can suit a range of instrumentations. I was glad (GIA) is worth considering for a more upbeat option and would work best with a soloist or choir leading the verses while the congregation sing the chorus.
Response
The Gospel focuses on being ready for Christ’s coming and you could use songs such as Christ be our light (CH 543 / MP 1201), People look East. The time is near (CH 281), Christ is coming! let creation (CH 475) or View the present through the promise (CH 479), with Sine Nomine a possible alternative tune for the latter. Bands might want to consider the new song All the earth was waiting (Resound) while Wait for the Lord (CH 276) and Word of the Father (CH 480) are two beautiful short songs which would also work well and which could be used as prayer responses.
Many of the songs suggested for the Gospel could also be considered for the Epistle. You could also consider the classic Advent hymn Wake, awake! for night is flying (CH 278) which would link to v.11, Soldiers of Christ arise (CH 515 / MP 604) and O church arise (MP 1213 / CCLI / Getty) which would link to v.12 and “put on the armour of light” or Goodness is stronger than evil (WGRG) which can speak more generally into the whole passage.
Behold! the mountain of the Lord (CH 715) and In the days to come (GIA) are both excellent songs directly inspired by the Old Testament passage. You could also look at songs on a theme of peace between nations such as ‘I have a dream’, a man once said (CH 710), For the healing of the nations (CH 706), Christ is the world’s true light (CH 456) or Ososo / Come now O prince of peace (CH 275), a short song from Korea.
Sending
You could use many of the songs already suggested to finish with, particularly Come, thou long-expected Jesus (CH 472 / MP 102) and Christ be our light (CH 543 / MP 1201). You can also consider other songs which focus on waiting for Christ to come again including 'Thy kingdom come!' - on bended knee (CH 473) with its excellent line "gird up your loins, ye prophet souls, proclaim the day is near", Make way, make way for Christ the King (CH 279 / MP 457), Everlasting God / Strength will rise (CCLI) or The time has come (WGRG) which is set to Sussex Carol and sends us out preparing to "protest, praise and dance".