For American mass-produced furniture from the period, Drexel may today be considered second-tier. But they did make an effort to hire domestic design talent and their construction quality in the '60's-'70's was superior to most of what was commonly available at the time. I have a Drexel sofa in my living room that I would put up against Knoll for appearance, functionality, and overall quality any day. And I'm sure that, at the time, it cost half as much which, IMO, makes it appropriate for my 1963 vernacular "American Modern" house.
As for your leather tops, minimal treatment is recommended if you don't want to replace them. If they were mine, I'd embrace the fading/discoloration as evidence of age and put a coat of wax (Renaissance) or quality boot dressing on them, buff with a horsehair brush, and call it good. A good rub-down of the wood with naphtha followed by airing-out and paste wax should help with the burnt tobacco odor.
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