Often people will have a single layer of clothing for their legs. Generally legs need less protection from weather than the torso for several reasons. Moisture management is typically less challenging and in most activities (other than climbing) your legs generate more heat than your arms because you are using your legs to propel yourself. Legs also tend to be more sheltered from rain than your upper torso. All these factors means that the comfort range of pants will tend to be wider than clothing for your torso. The most significant challenge presented by legs is that they tend to get abraded more than your torso, so pants generally need to be more durable for an equivalent lifetime.
Caveat: I use the same clothing for around the town, at work, while traveling, and for outdoor activities like backpacking, camping, and hiking. My absolute requirements for pants are they are made from a quick dry material than is reasonably durable, no giant cargo style pockets, no obviously reinforced bum/knees, no zip-off legs, good cut, and has pockets that are deep enough that things don’t fall out when I sit down in a chair that slopes back. Extra credit if the material looks like classic chino twill on the outside, lightly calendared on the inside for comfort, doesn’t have “discreet” inseam pockets on the side of the leg, no prominent logos, and doesn’t have a built in belt.
When engaged in in high energy activities and the temperature is above 45F, or lighter activity when it’s more than 65F I wear Outlier New Way Shorts. When backpacking I typically bring a pair of the now discontinued BPL Thorofare Trekking Pant or Zpacks Vertice Rain Pants to layer over the shorts. In cooler conditions, or when culture standards require long pants I use Outlier Slim Dungarees. If I am engaged in some sort of high energy activities (running, cycling, fast packing, etc) I use a pair of Zoot Tri Shorts because they have elimated chafing in the most extreme conditions. I am still looking for a pair of long pants which I can wear in >80F conditions which won’t chafe after 15+ miles of walking.
I am very fond of the materials, fit, and styling of my Outlier New Way Shorts. I am sure there are a number of other options which would provide similar styling and performance at a lower cost.
As noted above, when it’s above 45F and I am going to spend most of the time active, I wear shorts because I typically don’t need to worry about protecting my legs from bug bites or abrasions from vegetation. If it rains, I just let my my legs get wet because the heat my legs generate keeps me warm enough to be comfortable.
I also wear shorts a fair bit of the year, even when not engaged in some high energy activity. I tend to run hot, live/work in a locale with moderate to warm climate, and where casual clothing are acceptable.
Soft shells have been gaining popularity since they are comfortable over a wide range of conditions and tend to be made from durable materials. I have a general post about softshells. A quick caveat, I have yet to find softshell pants that I am happy to wear in hot weather. When it’s above 80F and I have to wear long pants, I prefer fabrics which are lighter weight than any softshell I have encountered.
I really like the pants made by Outlier. They fit me well, made from excellent fabrics (many Schoeller fabrics with NanoSphere treatment). They seem expensive, but I found they cost about the same per day compared to Levi jeans due to durability. There are a number of other quality travel friendly softshell pants. Maker and Rider also makes some nice soft shell pants as well as some very nice 4 season pants made from wool.
If you don’t mind more “outdoors” styling, there are a number of excellent softshell pants made specifically for climbing, skiing, etc. Many of these are make from Schoeller Dryskin. For many years I used a pair of Marmot ATV for cool to cold outdoor activities. The ATV pants were comfortable when I was active down to 15 F (skiing, snowshoeing, hiking, moderate duration ski lift rides) and still acceptably comfortable when it was 45 F and I was engaged in demanding activities. They were even comfortable when I was inactive in 70 F (eating lunch inside a lodge). If I expect conditions to be below 20F, I add a mid-weight base or a wind shell.
Classic Nylon “Hiking” Pants
Pants make from classic supplex or other light but durable nylon fabric. While not quite as comfortable as some of the softshell materials, they are less expensive, pack more compactly, and dry faster. Most outdoor clothing manufacturers make nylon pants: Campmor, Columbia, Ex Officio, Mountain Hardware, REI, Royal Robbins, TNF, etc. Ex Officio seems to use a lighter fabric than many which is nice in the summer because it’s a bit cooler.
The primary difference between the various manufacturers is fit, pocket configuration, and whether that have integrated mesh briefs. I would suggest going with whatever pants fit well and have a design you like. In the past Mountain Hardware and Ex Officio made pants that checked all my styling / feature requirements, but no longer. It seems almost all hiking / travel pants end up with a thigh pocket which I dislike. I consider Patagonia Quandary the best of the bunch. While I don’t always agree with their rankings, OutdoorGearLab.com Best Hiking Pants is a good round-up of some of the best options.
Some people like convertible pants since they can worn as pants when it is cool and then convert to shorts when it warms up. My first pair of Ex Officio convertible pants have been worn at least twice a week between 1996 and 2006, plus many successive days on every trip I took until between 1996-2004. They were still in good shape when they were retired, I just stopped using zip-offs. Part of the reason was my wife really disliked them, but I also found the zippers could chafe on extended trips.
I have a general post about rain gear. As for rain pants, there are a variety of theories. Some people believe that legs work hard enough that rain shell for legs is typically not needed. In warmer conditions this works well for me, but when the temperature dips below around 45F I found that I don’t like soggy pants on my legs and started to carry rain pants. I am using a Zpacks Vertice Rain Pants which work pretty well. My experience is that my legs produce less moisture than my torso, so I don’t have to be as picky when it comes to breathability for rain pants as well choice a rain jacket. Pretty much anything that is sufficiently durable would work for me.
Kilts / Skirts
I know a number of men and women who like using kilts, skirts, or even full dresses when traveling, hiking, and backpacking. Mountain Hardware makes a Kilt designed for outdoor use which seems to be a cult favorite. I experimented with hiking in a kilt, but could never bring myself to use one on a real trip. I guess I was afraid the fashion police would get me.
One think I did use for awhile was a rain kilt. I found these pretty effective, but ultimately switch back to rain pants because I found them more versatile.
Many people require little insulation for their legs to feel comfortable while being active, but it’s also important to remember that your body is a system. Your upper thighs come just after your core torso and head/neck areas in the amount of heat you can lose. So even though you legs tend not to be as affect by cold, insulating your upper legs can be a big help if you are trying to stay warm. Several companies including Mountain Hardware and Montbell make insulated skirts / kilts.
There are several ways to keep legs warm. For most people a base layer plus a shell work well or one of the warmer softshell pants. There are a number of companies which make down or high loft synthetic pants. As mentioned above, there are companies that make insulated skirts.
Chafing = Wetness + friction. Something to keep in mind is that you want to minimize chafing. One of the most effective solutions to minimize friction against the skin is to wear tight fitting boxer-briefs, biking shorts, or tights which are made from nylon or polyester with lycra. A number of people I know really like Under Armor compression shorts. Some people apply products like Glide as a preventative measure. I found that Glide did significantly reduce chafing, but I thought it was a bother to use, especially on trips which are more than a day or two. Wearing light, open, well breathing pants/shorts helps minimize accumulated moisture.
There are some new products which are base layers with stretch sections designs to compress and support your muscles to enhance performance such as those made by CW-X. I have no experience with theses, but they have gotten some good reviews.
Nylon warm-up pant or running shorts from Target, Walmart, etc.