If you've ever traveled for an extended amount of time, you've probably been told not to bring jeans along. Here's why you should ignore that advice.
When my husband and I left for our year-long honeymoon/trip around the world, we read a lot about traveling for months at a time. The most consistent advice was to pack light. (One guidebook even advised to drill holes in your toothbrush to save weight.) The other thing the guidebooks said was "don't bring jeans" - they are heavy, don't dry quickly and aren't comfortable on long flights. So, we dutifully headed to REI and North Face to buy things like zip-off pants (pants that can be both pants and shorts and, sometimes, also capris), fast-drying wrinkle free shirts and 3-piece hiking "outfits" that could be mixed-and-matched for lots of different looks.
Within a couple of weeks, we realized the error of our ways. We weren't hiking around the world, we were going to museums, having dinners out, grabbing drinks and cool bars and trying to blend in. Zip-off pants don't blend well. Jeans on the other hand can be worn from day to night, rarely need to be washed, hide most stains and look appropriate in many circumstances. We mailed our active gear home and bought two pairs of jeans that lasted the entire year.
Bottom line - pack your comfortable (not the tight ones that you can't sit in), versatile (remember the shoes you are bringing) and favorite jeans and you'll be good to go for the majority of things you do on your travels. And if you see an uncomfortable couple at a bar in Toyko trying to hang with the locals while wearing matching beige travel pants and hiking jackets, cut them a bit of slack because they'll figure it out soon enough and believe me, they are embarrassed too.