I'm extremely fond of my MEC Roubaix tights - they have a windproof front panel on the thighs Those are discontinued, but I believe the new version is called the Flyer. Cross-country ski pants or tights often have windproof front panels, too.

Softshell pants with a base layer underneath are my general cold-weather wear, for any outdoor activity.

Merino wool tights are available at Sock Dreams - Unique Comfy Colorful Sexy Socks and could offer a slight amount of extra warmth. Some base layers are thinner than others, as well.

Unfortunately, your friend may not *want* to wear any other layers, or different pants, but that's what she's going to have to do. Tell her to change when she gets to work; that's what I've done for 9 years.