This setting of "Now Thank We all Our God" is taken from Cantata 79 "Gott der Herr ist Sonn und Schild" (God the Lord is sun and shield) by J. S. Bach. Cantata 79 was written for Reformation sunday. (Remember Thanksgiving Day is an American Holiday which Bach didn't know any thing about.) If you look at the text of the hymn, it really doesn't say very much on the themes we like to think about on Thanksgiving day. That said, you might want to play this on the Thanksgiving Sunday, just the same. The title is perfect. But don't feel limited to the one sunday. Reformation Sunday would be perfect and so would nearly any other sunday. After all, aren't we thankful every Sunday? Shouldn't we be?
This setting is filled with possibilites. First of all, there is a version for 2 octave choir and a version for 4 octave choir. The big difference in the versions is that the 4 octave choir has the pulsing eighth notes that the tympany contribute in the orchestrated cantata. It's possible to do this in a mass ringing situation and a 2 octave choir can participate with a 4 octave choir and the two versions would fit together beautifully.
The Chorale tune can be played by a solo instrument (trumpet, or try it with a french horn). Note: a score for Bb solo instrument and C instrument come with your download. It can be sung by SATB choir. Chorale parts are available here for a reasonable fee ($5.00 -- which you can download, print and make as many copies as you need). If you want to spend the time and write them, feel free; it's up to you to decide what your time is worth. My only request is to make sure that the harmony matches . If all else fails, have your organist pick up the tune on the organ. It shouldn't be to hard to incorporate the tune into the continuo part. (you could also purchase the choral score and give that to your organist to incorporate.)
The keyboard part can be piano, organ or other keyboard. I think the coolest choice is harpsicord. When I did it, I used a keyboard/synthesizer 'harpsicord' sound and that worked very well.
For God's sake, be creative when you present "Now Thank We All our God" in worship. Use your resources. And be thankful.