Men with a taste for buttoned-up classics often depend on their clothing to be like that old pop song — wearable “always and forever.” But just as a favorite tune can wear out its welcome, so too might the shape or construction of a classic blue blazer. A survey of traditional menswear shops on the East Side yields a surprising amount of novelty, as their proprietors strive to make new friends but keep the old.

The shop windows at Paul Stuart (10 Madison Ave. at 45th Street, 212-682-0320) are devoted to the newly created, limited edition Phineas Cole line. The fictional Mr. Cole is billed as the “wayward son” of Paul Stuart. The line is something of a magic act, drawing Paul Stuart’s playful way with color and pattern into a leaner, cleaner silhouette. The chest is narrower, the armhole is higher (on coats, as well as shirts), the sleeve is narrower, and the shoulder is roped. Suits retail for $1,384–$2,384.

The diffusion line also plunges into sportswear and accessories: A slim pair of cotton moleskin trousers in mustard yellow ($398), a double-breasted blue wool cardigan with a leather throat latch ($897), and mid-calf cotton socks with a purple and black bold zigzag stripe ($39.50) are standouts.

Nearby, at the recently relocated J. Press (380 Madison Ave., between 46th and 47th streets, 212-687-7642), the three-button sack suit has its strongest defenders, veering modestly into bolder territory by offering a tiny herring-bone pattern that previously existed only in a gray worsted fabric. Still, with the relocation have come minor shifts for J. Press — a two-button blue blazer ($425), for instance. Although the look first caused a stir when popularized by President Kennedy in the early 1960s, in the formal world of J. Press, such a change can still cause ripples. Some of their suits now feature darted fronts, double rear vents, and even pleated pants.

In its narrow but surprisingly deep store, H. Herzfeld (118 E. 57th St., between Park and Lexington avenues, 212-753-6756), in business for more than a century, employs some of the most traditional business practices in this New York haberdashery. There, prices remain the same until the item is sold. The result? Some happy disparities. Although a cotton-and-silk sport coat by Adrian Jules (Hickey Freeman’s Rochester-based rival) costs about $1,500, the same sum might net you a full gray suit by Belvest of Italy, which Herzfeld still has in a few odd sizes. At Herzfeld, the question “What’s new?” is met with a smile, and a shrug. Climate-change-friendly, lightweight fabrics and the slightly slimmer Jules silhouette are the beloved shop’s nod to the contemporary.

At Jay Kos (475 Park Ave. at 58th Street, 212-319-2770) every piece pops with color, except, perhaps, for the burnished browns and blacks of the Edward Green shoes (but even these, like most of the items at the store can be made to order). A preppy palette rules at Jay Kos, and in the quest for new color and fabric combinations, the store has scaled the Matterhorn of luxury: This fall, for instance, a classic blazer in a lightweight cashmere hopsack weave comes in purple ($4,500).

At Peter Elliot Blue (997 Lexington Ave. at 72nd Street, 212-570-2301), $4,500 will buy you a cashmere sport coat by Kiton of Naples, but the real draw at this blazer-oriented boutique comes in the form of two models by Barena of Venice: One, made from wool flannel, has deep pockets for game and a shooting-patch-style shoulder, while the other is made of wool jersey knit, with unfinished seams ($900 and $695, respectively).

Ralph Lauren tweaks and trims his offerings to clothe the widest range of style-minded American men at the Polo Mansion (888 Madison Ave. at 72nd Street, 212-434-8000). The suits stocked on the upper level bear the mark of Mr. Lauren’s ex-employee, designer Thom Browne — known for his tailored, shrunken suits. While the high-end Purple Label collection has relaxed slightly, the early-1960s-inspired Black Label is more restrained than ever. But the most contemporary silhouette is in the sub-line of Polo’s Blue Label, Bleecker. It is Mr. Lauren’s answer to Mr. Browne: shorter, sharper, tighter, and this season occupying its own room between the Purple and Black zones.