I present to you Sartorially Inclined's Khaki Shirt Primer:
Head designer Patrick Robinson keeps things casual, classic and most of all, wonderful yet again. This guy really knows what he is doing and this khaki shirt from the American institution known as The Gap is another affordable classic piece (they keep churning 'em out these days). Definitely the most casual of the bunch, this shirt would look great thrown on wrinkled, much like your pinpoint oxford. Leave the tie at home, untuck and maybe even unbutton (undershirts required).
The more expensive older brother of The Gap is getting in on the action as well with a crisper, more dressy option. The shirt appears to have a higher level of detailing (red thread on the top button), as well, which is always nice when attempting to justify price. I like this shirt as a dressier option, i.e. tucked in with a rep or knit tie. I can see this shirt being much more of an iron before you go out as oppose to a tumble dry. Just keep in mind that when it comes to Banana, price doesn't really reflect quality...
The champions of mainstream heritage return with their take on the classic. Seemingly bucking the khaki color, they instead offer their chino shirt in both a fall friendly gray and bisque (their fancy way of saying "whtie"). If you already own a grey chambray or denim shirt, I would skip this option since unless you plan on being fondled (and you just may) not many people will be able to tell the difference. On the other hand, if the khaki color is not your speed, this might serve as a great compromise.
There are lots of great options out there so don't feel like you need to wear flannel, chambray or otherwise. As long as you stay informed there is never a need or reason to be trendy or fashionable...find a shirt that looks great, fits great and, most of all, feels great...I imagine you're likely to find a khaki shirt that is all three...