During the run of "Captain Henry's Maxwell House Show Boat" on NBC Radio (Thursday nights, 9pm. First show: June 15, 1933), Maxwell House Coffee ran a series of magazine ads promoting the show. These full-page advertisements appeared monthly on page 6 of The Saturday Evening Post over the course of 1933 to 1937. Listed below are the dates of the The Saturday Evening Post "Captain Henry's Maxwell House Show Boat" ads and their subjects. Click on date for image.

1. August 12, 1933. Full cast - Molasses & January, Charles Winninger (Captain Henry), Annette, Lanny Ross, Edmund "Tiny" Ruffner, & Muriel Wilson (as "Mary Lou").
2. November 4, 1933. Charles Winninger & "Maria" (Irene Hubbard).
3. December 2, 1933. Charles Winninger & Tiny Ruffner.
4. December 30, 1933. Charles Winninger.
5. January 27, 1934. Maria.
6. February 24, 1934. Annette & Tiny Ruffner.
7. March 24, 1934. Lanny Ross & Muriel Wilson.
8. April 21, 1934. Charles Winninger & Maria.
9. May 19, 1934. Charles Winninger.
10. June 16, 1934. Annette & Conrad Thibault.
11. July 14, 1934. Lanny Ross & Maria.
12. August 11, 1934. Charles Winninger & Maria.
13. September 8, 1934. Charles Winninger.
14. October 6, 1934. Full cast.
15. November 3, 1934. Lanny Ross.
16. December 1, 1934. Coffee pot only (no cast).
17. December 20, 1934. The Show Boat Four (Randolph "Tubby" Weyant, Scrappy Lambert, Leonard Stokes, & Bob Moody - and at the piano, Kenneth Christie).
18. January 26, 1935. Maria. Cartoon strip sequences begin with this ad.
19. February 23, 1935. Tiny Ruffner.
20. March 23, 1935. Lanny Ross.
21. April 20, 1935. Maria.
22. May 18, 1935. Captain Henry (New cast member as Captain Henry - not Charles Winninger).
23. June 16, 1935. Tiny Ruffner.
24. November 28, 1936. Lanny Ross & Tiny Ruffner (promo for 1937 edition).
25. December 26, 1936. No cast ("Captain Henry's Maxwell House Show Boat" promo at the bottom of ad).

I'm not sure where the "Captain Henry's Maxwell House Show Boat" ad series stops as this is as far as I took it since Annette appears to be no longer on the radio show. Note that Annette only makes four ad appearances.