My all-time favorite pant to wear when traveling rugged terrain is the Arc'teryx Witness ($89, arcteryx.com). It may bear a slight resemblance to your boyfriend's best pair of khaki cargo pants, but the fit is much more feminine, with a hip-hugging waist and two butt-diminishing back-flap pockets. A rock-climbing pant by design, the Witness, which comes in oregano, raisin, and sesame, has articulated knees, a gusseted crotch, and a side pleated cargo pocket on each thigh (where I stash my notebook and pen). The best part about the Witness is that it easily dries overnight. While khaki is cool, I'd recommend the darker oregano or raisin so you don't feel like you have to wash it every time you kick up a little dirt, say, on the way to Machu Picchu.
For flying long distances, I like a wool, yoga-style pant because they're warm, comfortable, keep their shape, and feel good. One great option is Ibex's Loose Tights ($135, ibexwear.com). The 89 percent merino wool tights, which look much more like pants than tights, come in basic grey, black, or brown. They have a comfortable three-inch waistband, a zip pocket at the waist for stashing extra cash, and a boot-leg cut. Just because it's wool, doesn't necessarily mean you'll overheat, especially in high-altitude. Machine-washable, you can hike in it by day then wear it out the same evening without feeling like a hippie Gringo, even in those nightclubs above Bogota.