If you're not going to treat the end of the Vigil still as a historical reenactment by treating the Nativity as strictly-yet-to-happen, you can use an emphatic sung recessional of a kind that people expect at Christmas Masses; there are two heavyweights in the USA in that regard, and a middleweight that is the most likely next choice after them. I strongly prefer the middleweight: that is, Angels We Have Heard on High, over the two heavyweights (1) Hark The Herald Angels Sing or (2) Joy to The World. (The last thing I ever want to hear is Silent Night done like a huge recessional anyway.)

There are many wonderful hymns that would suit if something less so emphatic were desired, but I am not sure they are things American Catholic congregations would be as likely to join.

If someone had written a clearly Christ-centric version of It Came Upon The Midnight Clear, that would been perfect for this.

I've thought long and hard about carols at Christmas Masses, but I have to say the Vigil is difficult. In short, I agree with Liam and would go with one of the popular choices he suggested.

When it comes to hymns appropriate for the Vigil, the following hymns and carols come to mind:

For the Vigil specifically (a mix of late Advent, early Christmas, and hymns related to both):
Lo How a Rose Ere Blooming
Alma Redemptoris Mater
Come Thou Redeemer of the Earth (Veni Redemptor Gentium)
(Come Thou Long Expected Jesus)
(O Come Divine Messiah)
(O Come O Come Emmanuel)

For when the Vigil becomes the "Children's" or "Family" Mass:
Once in Royal David's City
Infant Holy Infant Lowly
Silent Night
(Away in a Manger - only if compelled)

For night-time:
O Little Town of Bethlehem
Sussex Carol

Popular carols, and those that should be more popular:
O Come All Ye Faithful
Joy to the World
Hark the Herald
Angels we have Heard on High
In Dulci Jubilo
A Great and Mighty Wonder
Of the Father's Love Begotten (Corde natus ex parentis)

When it comes to recessionals, given you haven't included any of the 4 most popular carols for Christmas Mass (those Liam mentioned, along with O Come All Ye Faithful), I'd go with one of those three. But if you're looking for something different, possibly In Dulci Jubilo or Sussex Carol. And you can't go wrong with the Marian antiphon.

[EDIT: To be clear, I do not recommend "O Come All Ye Faithful" as a recessional; I only mention it as being common, and popular, and good.]

That's lovely! Thank you for sharing it.

I have this thing about doing processional texts as recessionals: please don't. Please don't do texts whose first verse says COME to the altar as ... people are about to leave. (The Old Hundredth with usual first verse, and Praise to The Lord The Almighty, et cet.) I've encountered DMs who don't appear to care about this, but there's a reason I didn't mention OCAYF for a recessional. Yes, it's the super-heavyweight metrical hymn for Christmas; it's lovely when English and Latin verses are alternated when you have the opportunity for a very long procession.

If I were not familiar with American Catholics' typical repertoire, I'd be able to recommend hymns like Sussex Carol, Ding Dong Merrily on High, Infant Holy Infant Lowly, See Amid The Winter's Snow, In The Bleak Midwinter (Holst or Darke, preferably both over the course of Christmastide, thank you kindly), et cet. With each passing generation, fewer American Catholics have a solid memory of religious Christmas hymns sung as hymns; religious Christmas greeting cards (well greeting cards in general) are where Easter greeting cards were 30 years ago.

I have a special place in my heart for an American classic, I Wonder As I Wander, but realize it's place is not at the processional or recessional.

(As an aside: Singing "See, Amid the Winter's Snow" for the first time at an Episcopal church in Champaign, Illinois---Heath will know exactly where---was one of those moments on which I look back and think that there was God calling me into the Catholic Church. This experience is one of the reasons why I do not stop working when other Catholics imply that the Catholic Church does not need or cannot sing my work. Other churches use Catholic material.)

PS: For folks unfamiliar with Richard Marlow's way with descants*:

https://www.youtube.com/watch?v=u6NXeX7P5Io

https://www.youtube.com/watch?v=E8T2p53-bwY

* Btw, hymn descants as we have come to know them in the past century are a fruit of . . . World War I, when church choirs in the British Isles lost a lot of male singers to military service and injury/death, and composers/arrangers took a trick out of the bag of 16th century practice to make something of the reduced choral forces.

Ah, all good. Thanks for the clarification. I love the hymn, and know I will likely never hear it at a Catholic parish in the USA. Sad.

Liam, im so intrigued. Cannot find scores anywhere, even used. They are all out of print, sadly.

I’m with @Liam on this one. Unless you live in an area where people are seeking out traditional and/or English Choral type masses, play it conventional. We all get a boost of CEO (Christmas and Easter Only) Catholics and those specifically going to Mass to sing Christmas carols. Give em what they want. Save the unique music for Christmas Day, the Christmas Octave, or any of the other masses in Christmastide, IMHO.

That being said, great stuff you picked.

My money’s on Joy to the World or O Come All Ye Faithful.

Allow me this one grump: Joy to the World does not mention Jesus' birth of the Virgin Mary. I'd prefer Hark! the Herald Angels, even if we haven't heard the angels sing at the Vigil Mass (if father is following the Lectionary and the Missal).