Patek Philippe are not known for hi-tech carbon composite case materials, skeleton dials, or really any enthusiastic contemporary flair. What they are known for is being the priest of the Temple of Classicism, considered and purposeful in any direction of development, refusing to bend to ephemeral market tastes. The clearest way this can be seen is how little the design DNA (yes, I know you think that term is overused, GaryG) of their watches has changed over the last century.
This lack of dramatic change forces those interested into the trenches of granularity to ascertain the importance of any particular Patek Philippe reference, specifically in the Calatrava family. One watch that appears perfect initially, and remains perfect no matter how close you inspect it, is the ref. 2526. The ref. 2526 is, in my mind, less of a watch, and more the platonic ideal of a watch, something you might show to an alien to communicate the perfect example of what a watch should be.
One of the best-looking examples of a Patek Philippe ref. 2526 is the one pictured above, in yellow gold with a black enamel dial. Fortunately for all of us, GaryG wrote an article for Quill & Pad on why he bought it, and what his impressions of it initially were. Wear it in good health, Gary.