Yes, if I'm willing to have a multi-part series on the value of a good poop-scoop, then it's probably no surprise that I have no shame in addressing the value of good underwear too.
If you haven't been victimized by chaffing, you're really missing out on a wonderful experience of pain tolerance. Chaffing, specifically thigh-on-thigh chaffing is a very unpleasant experience. In fact, it can ruin a hike. Despite being armed with Hydropel and wearing ExOfficio boxer briefs which I thought were sufficient, a couple summers ago I got the pleasure of feeling what I described as being bit in the crotch by a rabid Rottweiler which took a couple weeks to heal. Simply, it hurt to walk and there was really no good way to deal with it other than by being patient and sitting quite patiently in an exposed and vulnerable position.
In the end, for my situation anyway, the most help I could gain to ensure it didn't happen again was to be more selective with my underwear choices. For this reason, I'm going to propose three solutions. First, as mentioned by Ray Jardine and others, simple spandex or polyester "biking" shorts can do double duty as both shorts and underwear. If you can find some treated with silver, you'll gain better anti-microbial properties. Second, as I mentioned in another blog, I've also had some luck wearing very wispy shorts with interior netting for support. The ventilation helps tremendously and as long as you can keep the fabric from bunching up it might just be a good option for you. That leads me to my third point, proper fitting underwear.
As I mentioned, in the past I used ExOfficio snug-fitting boxer briefs which are pretty common in hiking and traveling circles. For me, they simply didn't work well enough for me to keep using them. I then moved on to a pair of Under Armor boxer briefs which were far more robust, more snug fitting, and did their job better. The problem is they run $20-$30 per pair. Simply - this is ridiculous.
For quite a while I've been searching for something on par with Under Armor. About six months ago I stumbled across what I would later learn to be their replacement. Unfortunately, I wasn't able to find them again until very recently and I elected not to blog about them until I was able to say they were still being made and could be found by my readers. 
So here's the best option I could find...which I prefer over Under Armor. They are significantly cheaper, slightly lighter, and craftsmanship and materials are on par. Yes, and they do the job. Under the STARTER brand name and only available at Walmart, check out the Active-Pro Performance 6" Boxer Brief. They are just $8.88, come in a variety of sizes, and honestly, they are the best underwear I've owned for backpacking as they are just as robust as UA, but just slightly thinner which is helpful for quick drying. Here's the thing....you can't find them online and I've learned that some Walmart stores have them while others do not. Simply, you need to put in the time to try to find them. They exist. Some Walmart's have a huge section dedicated to them while others only have the cotton version.Butt Paste, zinc, and other baby-related creams go a long way too, but that's for another discussion. I even know of one hiker who dabs alcohol from cotton swabs onto the irritated area. He claims it hurts tremendously, but quickly makes all the pain go away.
Happy trails.
