Milestones are a trend this Milan season, and on Friday night, Trussardi marked a century with a big bash at Castello Sforzesco and the first women’s collection by men’s wear designer Umit Benan Sahin. The airplane seats on the backdrop stage pretty much said it all: These were clothes destined for the woman who likes to rack up her frequent-flier miles. The show notes cited “the allure and charisma of a young Diane Keaton” as an inspiration. Think relaxed, wearable, slightly mannish and a bit of jet-set chic without flash, including belted blue blazers teamed with casual trousers, trenchcoats with alligator collars, perforated leather tops and cool suede tunics. Benan Sahin’s challenge was to create a lifestyle around a brand that is still best known for its leather goods. The looks never overpowered the accessories, but nicely complemented the canvas weekenders, leather suitcases and colored python briefcases.