Okay, after some more noodling around I find that at
http://alexa.amazon.com I can select the Echo and then the Music and Books sidebar link to see my music library and Amazon playlists and stations, Pandora, etc.
And there, at Amazon Music --> Playlists --> Genres --> Holiday was that Acoustic Christmas "album." I couldn't back out of that string, btw. Had to hit the sidebar link for Music & Books and start back at the top.
So, theoretically, the answer to my original question is "sort of."
(The artists links are indeed random shuffles of music, as though you'd told Alexa to "Play Dexter Gordon.")
I use the Amazon Music app, which does allow you to add the entire album at once.