Depending on the weather and duration of hike, you may want to pack both pants & shorts. Below are some suggestions:
LEGS
Quick-dry shorts
Throw these on under other layers for when the sun begins to beat, or you have a sudden urge to jump in a glacial lake. Lightweight, durable and comfortable. NO COTTON.
Patagonia: Baggies™ shorts
Marmot: Yonder Short
Mid-Weight (2 pair)
Fitted, light-weight and quick drying. The mid-weight will be a base-layer that will get you through a wide range of temperatures.
Patagonia: Capilene® 2 Bottoms
Marmot: Midweight Bottom
Expedition-Weight Bottoms
Warmer than your mid-weight, but still breathable and lightweight. These will be worn around camp and on summit day.
Patagonia:R1® Pants
Soft Shell Pants
You will spend most of your days in these pants. Choose Schoeller® or a soft-shell equivalent. Breathable + water-resistant. We prefer lightweight models.
Patagonia: Guide Pants
Marmot: Scree pants
Hard Shell Pants
Your waterproof bottom layer for extreme-weather days. Make sure you have water-resistant zippers, crampon patches + good pockets. Bibs are unnecessary- lighter weight (Paclite material) is best.
Marmot: Exum Pants, Oracle Pants
If you are doing kili, one good pair of hiking pants that can be converted into shorts is all you need for your main pant layer. Many people bring too much.