For those who can still get their congregations to add a service this week:
Here is the 1945 Minhat Todah- Service for Thanksgiving Day, Congregation Shearith Israel, NY by Rabbi David de Sola Pool.
Happy Holiday- Let me know if anyone uses it.
Thanksgiving Service- 1945 Rabbi de Sola Pool (pdf of full service)
There are several good sermons from Rabbi Leo Jung for Thanksgiving Sabbath and a couple of shiurim on the web from Rav Soloveitchik from the Wednesday on the eve of Thanksgiving. Here is one of my favorites from Nov. 22, 1975
in 2016, I posted a 1905 service for the Sabbath before Thanksgiving written by Rev H. Pereira Mendes of the Spanish- Portuguese synagogue of NY
And in 2014, I posted the Thanksgiving service from Kehilath Jeshurun 1940 and prayer from Rabbi Joseph Lookstein.