I'm a Clark Fit kind of guy (5"10 165 lbs.). I'd consider it a classic fit, such that it's straight through the hip and thigh with a straight to slightly tapered leg. They make for a great-looking, comfortable pair of chinos for the office or for dinner out (paired with a blazer of course).
The Brooks Brothers Fit Guides used to be displayed in several different departments of their online store, but unfortunately they were removed for a long period of time. Luckily, the Brooks Brothers Pant Fit Guide is back on their website. I'll keep checking the Brooks Brothers website for the newest versions of their Fit Guides so that I can bring them to you.