THANK YOU , EVERYONE, FOR ALL THE GREAT COMMENTS AND SUGGESTIONS.
I PLAN TO TAKE EVERY SINGLE SUGGESTED DETECTIVE AND A FEW MORE AND PUT THEM ON THE LAYOUT - in time. Further below, after the photos, I'll make some comments and respond to some suggestions. But first, I have three more detective cars and five more detectives now - including the car and detective that triggered the whole idea for all this "cowboys."
I appreciate all the suggestions. The original idea was limited to detectives heavily associated with their cars: Morse and his Jag, etc. I expanded it somewhat and now have decided to open it up to any and all famous fiction detectives, particularly TV and movie ones: my layout's scenery will have two themes; Veranda Turbine, on the layout in about a dozen small vignettes, etc., and as many detectives as I can cram into it. Above, you see Nick and Nora Charles, and Nero Wolfe along with Archie and Saul.
If the original idea was detectives associated with cars, one has to wonder where Bullitt and Magnum PI are, and also Columbo, with his wonderfully clapped out Peugeot 403 convertible. Bullitt and Magnum will be on the layout later this week. Columbo is a challenge. I can't find a model 403 Peugeot convertible (of the appropriate vintage), and will have to modify a 403 model delivery station wagon into his convertible, or scratch build the car - either would be a ton of work, so I may just wait it out to find a good model of the correct car.
As to Phillip Marlow, I'm having trouble determining and finding exactly what car he owns. I've studied a lot of google photos and articles on him, and can't find a model anywhere that matches. So, he will be on the layout this afternoon but with a '35 Ford 5-window coupe, close enough for now.
Anyway, Lord Peter Wimsey and Harriet Vane with his absolutely stunning '31 Daimler Double Six will be on the layout in a little while - working on that now. But I have to move something downtown, on Main Street - that car deserves to be easy to study !