I'll disagree, SB. Khakis make for a casual pairing with sportcoats, yes, but the combo has an unquestionable pedigree. It's been a mainstay of the Trad/prep/Ivy look in the decades since WWII. Beyond that, khakis and tweed are both rustic, casual cloths.
SF hasn't much cared for the look, but I suspect that has a lot to do with the pendulum swing of formailty many of our posters experience after finding/seeking out the forum.
I don't question the pedigree of khakis with SCs, but I don't think that particular variety of SC is a natural fit for them. They look okay with hopsack, but pretty wimpy with tweed. The more pronounced twill of heavier cloths works better, though, than the typical example seen here, which is part of why I think gdl's work okay above.
It's an interesting discussion. As I said, I'm in the minority on SF where everyone seems to want to wear grey wool pants with their sport coats.
That said,I can say with a very level of confidence that nearly 100% of my sport coat outfits are with cotton pants. So not really new news here...
i also like brown pants and blue pants and tan pants.
i dont have any decent cotton pants, but come summer, i may get a few and try out the gdl steez, see if i can handle it.