I've used Banks' in-house fitting/tailoring to satisfactory result. Your results may vary by retail location; at the location I've used, substandard results simply won't be tolerated (discriminating consumers).

At Banks, sales are definitely a way to go (and, for suits and trousers, help defray the cost of a good fitting). As a separate example, they have had some of the best-fitting polo/rugby shirts I've found. They are normally rather pricey, but if you pick them up at the end of summer they are quite reasonable.

A book that used to be heavily recommended is "Dress for Success". In essence, the recommendation and instructions are to learn to know and then insist upon certain rather conservative but attractive styles that never go out of fashion.

"Dress for Success" appeared some years ago to have entered that perpetual "revise and republish" life, similar to, for example, the career advice guide "What Color Is Your Parachute" (a new version every year). I don't know what that means for its quality, compared to when the same edition continued to be valid and current year after year.

P.S. Thinking about what I just wrote, you may want to drive over to the part of town where discriminating people shop. If you're unsure, think of contacts who would know and get some local recommendations. If you can get a reliable recommendation to an individual salesperson, or perhaps even better, fitter or tailor, so much the better. (Assuming there are still some that haven't been squeezed out of the economy.)

Tell them what you're after, and count on their advice to steer you to quality items. Don't begrudge the markup that pays for this service, as long as it's not excessive.

I have several 10+ year old suits that are perfectly serviceable (thankfully, also fairly lightly worn), by virtue of following this route.

Hopefully, such service has not completely disappeared from today's marketplace. Again, you may have to drive to the right part of town to find it.