Destry is #113 on my List of Essentials and my favorite film of 1939, although in a year that produced Mr. Smith, Young Mr. Lincoln, The Wizard, Ninotchka and Mr. Chips among other classics I'm inviting unnecessary negativity with such a claim. (I doubt it could even make a noble effort against Stagecoach in a Deathmatch.) So, I'm glad you had a Great time.
Where I disagree with you is I think Destry is very much a Comedy, a Screwball Comedy at that. The pushover drunk deputy and his reaction to Destry's parables, the entire subplot with Boris' pants, including bartender Billy Gilbert (His Girl Friday). There's Allen Jenkins ("No more cheese"), and you won't find a more loose and goofy performance from Marlene Dietrich. I love the scene you mentioned with the makeup, but I also love post-fight when she sees herself in the mirror, the betting scene with Boris, and the moment where she trips over her furniture that I'm not sure was intentional. Destry's refusal to carry a gun is a comedy plot and even the somewhat dramatic climax has the broad inclusion of all the women of the town. (The one time where the polished narrative starts to creak.)
I don't want to overload your Marathon list, but in 1954 the same director remade the film, and
it's interesting to compare the differences. The cast of the remake doesn't have a spark of the charisma of this cast, but it does go for a more straight and serious ending, the one part I would say improves on the original, (though I love the way Dietrich relishes her big moment at the end.)
I don't know if you recognized Brian Donlevy. He's the one who starts all the trouble in Jesse James by strong-arming people out of their land and he's in Union Pacific, killing Indians for fun. He's really good at playing jerks. The scene in the image above is one of my favorite scenes in the genre. That's mostly a credit to Stewart for the way he disarms a tense situation, but like the "am I a clown?" scene in Goodfellas, it's the reaction of the other guy who isn't sure what to do that helps make the scene a classic.
I will agree with you about Destry not being a musical, but there's been talk around here recently about Earworm Songs and I would put "Little Joe" on that list, especially with Wash doing a 2nd version and a reprise at the end.
It's a film I can see myself returning to, time after time, if for no other reason than for James Stewart.
I told my wife that some people will probably be watching Destry Rides Again this month so I might want to re-watch it, and she replied, "I'm ready." I believe this is the 4th post I've written about Destry and they're all around the same length. I never get tired of talking about the film. It never gets old.