It's very easy for Advent to seem like the poor relation to Christmas musically and it can be tempting to start singing carols during these weeks to fit in all the favourites. However, sticking with songs which relate to the Advent texts and themes can really help engage with the radical message behind the Christian season as a contrast to the commercialised messages we hear everywhere else at this time. In year B there is a focus on the urgency of waiting for the coming of Christ and the transformation that will come with it, with a particular focus on prophetic voices we hear from the margins.
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. Even with singing not allowed in physical services this year there are also some great instrumental versions from The Piano Guys, Casting Crowns or the Organ Fantasia by Leighton.
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 this year then Christmas is coming (CH 282 / CP 34) and Advent candles tell their story (STF 165) would both fit the pattern of readings with its themes of Promise, the Prophets, John the Baptist, and the Virgin Mary.
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 (Iona), 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.
Psalm 80 does not have many well known settings. However, Restore us again (PFAS / pdf) would be easy to pick up and use responsorially. For a metrical setting, O Shepherd, hear and lead your flock (PFAS / Hymnary) is set to the tune used in North America for O Little town of Bethlehem, so you have the option to use that or to use 'Forest Green' which would hint towards the coming of Christmas for those in the UK. Shine on us (CCLI) is an option which focuses on just the repeated cry in verses 3, 7 and 19 rather than setting the whole psalm.
Response
Lord you hear the cry (Resound) is a great song with a gospel feel which explores what it means in Isaiah that the heavens will be torn open, and could also be used for intercessions. View the present through the promise (CH 479) looks at the the trust we need in Christ coming again and what that means in terms of how we live our own lives while we wait. Take heart (Resound) is inspired directly by the Gospel text and what it means for Christ to come in glory. Waiting here for you (CCLI) is musically challenging for a congregation who don't already know it and might normally fit best into an opening set but could be a really fitting response to a sermon looking at what it means to stay awake while its opening line also ties nicely into the mountains imagery in Isaiah.
I often find Advent is a good time to use Taizé songs as prayer responses, singing twice at the beginning to allow people to learn it then once after each stanza of the prayers. You can also have the instrumental accompaniment continue under the spoken prayers. For this week I would suggest In the Lord I'll be ever thankful (CH 772 / MP 865 / Taizé).
Sending
This is the Sunday in the three year lectionary cycle where one of the great Advent hymns fits with the Gospel reading, Lo, he comes with clouds descending (CH 477 / MP 424), which makes for a very appropriate ending as we look to Christ coming again. Also picking up on Christ coming in the clouds, but in a totally different style, is Days of Elijah (MP 1012 / CCLI) which hints at the themes of restoration we see throughout the passages today. Christ is coming! let creation (CH 475) resonates with the 'groans and travails' of creation which we see in the opening of the Gospel passage while tying Advent into the full cycle of Christ's life in the second verse. Did You Feel The Mountains Tremble? (CCLI) links with the mountains quaking in the opening of Isaiah while resonating with broad seasonal themes of hope, joy and the end of injustice. Everlasting God / Strength will rise (CCLI) also ties in with some of these broad themes and works well to conclude on the theme of waiting.