I used to live back east and hike in the miserable humidity. Because it was hot, I initially felt that a short-sleeved polyester shirt would be best, so that's what I used for a long time. But bugs (flies, horseflies, gnats, mosquitoes, etc) drove me nuts having exposed arms. And the biting types can nail you right through the fabric. When I switched to a long-sleeve RailRiders Madison River shirt, life was instantly better! The shirt dried extremely fast, and I was pretty amazed that I didn't really feel any hotter in it. And the bugs can't bite through the nylon, so that was a HUGE advantage. I eventually moved west and now spend my time in the High Sierras and find that the same Madison River shirt is my favorite. It provides great sun and bug protection and dries in minutes. So as I go in and out of buggy zones along the hike, I'm not a bit bothered if I look down and see 5 mosquitoes on the front of my shirt, because I know they can't bite through it. Not the case with other fabrics. I also love that I can unbutton the front for ventilation while hiking, and the mesh strip up the sides helps with this as well. I wear not only a long-sleeve nylon shirt, but also nylon pants and a big ole Sunday Afternoons sun hat, so in terms of exposed skin, that really just leaves my hands and front of my face from maybe the nose downward. So I don't need much sunscreen. I read online this year of people complaining of the terrible mosquito pressure in the Sierras, yet I spent a considerable amount of time in the Sierras this year without a single bite...no doubt because I'm wearing stuff they can't bite through. I never once resorted to using DEET, which I had with me just in case. Sometimes when hiking, I'd look down and see 8-10 mosquitoes on my pant legs. I wouldn't even bother to swat them, because they'd just eventually go away on their own. The folks with lots of exposed skin were being eaten alive apparently.
I'll also add a note on the R.R. Madison River shirt compared to the Bone Flats shirt. Despite what R.R. advertises about the Bone Flats being "ultralight," it actually weighs almost an ounce MORE than then Madison River shirt. The fabric on the Bone Flats IS noticeably thinner, but the response I got from R.R. was that it weighs more because there is additional fabric in the shirt. Where? I have no idea. And why their advertised weight of the Bone Flats isn't even CLOSE to its real weight is also a mystery. I'm not too happy about their failure to correct the weight of the Bone Flats shirt in their product description. Regardless, I'll keep on loving my Madison River shirt. It freakin' rocks!!