Hello Pooh,
Your thread is big enlargments from 35mm. Well I've made 20"x24" from 1000 asa Kodak 2475 High speed recording film souped in D-76 exposed through a Nikkorex camera. Grainy but beautiful. Considering the subject matter and the extremely low light I'm well pleased. I could not have gotten the shot with any other film at that time in the 1970s. Possibly EK2484, but I doubt it.
My biggest, sharpest, grain free enlargments with a 35mm were printed to11" x 14" with Plus-x pan souped in D-76 stock solution, exposed with a Canon FT-QL with a 50mm f1.8 lens. Sometimes I'd use Microdol-x 1:3 but I did not like the loss in speed. Plus-x pan and D-76 with Tungsten "hot lights" gave nicer results than electronic flash.
I've tried Panatomic With microdol developer and was not sold on it.
I've tried H&W Control VTE with its dedicated developer, not amazed.
I've tried tech Pan with Technodol, interesting but not jazzed.
I've used Ilford Pan f with Perceptol, similar to Panatomic and microdol.
YES, I've used Zeiss and Leitz glass with the above films and YES I've used 20 pound tripods and a cable release with testing the above films.
Coming from the era of using 8x10 cameras and a 4x5 Graphic daily with flash bulbs, I think the run of the mill, average 35mm negative runs out of steam at a print size of 5"x7" and really looks its best no bigger than 4"x6". HOWEVER, a 35mm negative with a proper exposure, a good lens, carefully developed, printed with a good aligned enlarger with a lens equal in quality to the camera lens can be made to breath taking beauty at any size. It's just harder to do with 35mm than with a larger negative.
All the best,
Sam H.