Staying warm in the north east winter, women's pants...

[Damselfish]

If she wears her jeans on the tighter side, definitely go for more form fitting long johns. Long johns trying to bunch up under her pants will be annoying.

Fleece pants (the kind you wear separately, not under something) are very comfy, but not very dressy. Kinda like fuzzy sweatpants, so might not be party material. (Guess it depends on the party!) Something to keep in mind about fleece, unless you can get something made with one of the wind-block type fleeces, a stiff wind will go through it so it will much less warm if it's windy.

 

[divad]

Just get her black silk long underwear. It's super thin, light, incredibly warm under jeans, makes great pajamas, and unlike fleece-lined pants, won't make her feel like she's wearing "MOMS". Plus its a nice gift. A girlfriend bought me my first set because she liked it on me, now I just wear it because it makes me feel fancy.