best sun hat

I really like the OR sun-runner and use it year round.

Sunday Afternoon Adventure Hat.

Dorky looking but very effective.

Has a wide brim in the front and a "tail"/flap at the back that completely covers your neck.

http://www.sundayafternoons.com/store/adventure-hats.html

-Tony

Whatever you buy, I would stick with a WP/B hat so it can double as a rain hat. Using a rain hat instead of a hood on a rain jacket is so much better in the rain.

Most comfortable and best sun protection I've found; yes, it's dorky but when you need to protect your skin dorkiness sometimes has to be endured…

If you absolutely can't tolerate the floppy back, Sunday Afternoons has other styles that look more conventional but still provide good wide brims.

For something that covers the side of your face and is very light:

http://www.sunprecautions.com/shop/unisex_mens/hats

Scroll down to the bottom of the page for the Shade Cap with Crossover Drape.

I wear their shirts and love them. I do wear a Sunday Afternoons Adventure hat that I like a lot.

The Outdoor Research Sun Runner is a good hot weather hat with a drape to give full protection of your neck and the sides for your face. 2.8oz.

http://www.outdoorresearch.com/site/sun_runner_cap.html

Or you can make your own with a baseball cap and bandana.

Good call on using more protection. I use the OR sunrunner hat as well and it works great. A little dorky but none of the full coverage hats are going to look "cool". Its nice and light. The Sunday Afternoon hat looks pretty good as well.

The best would be a Mexican style sombrero. Anything with wide brim, open and good ventilation.

I personally don't like the Sunday Afternoon style as the back flap and droopy brim blocks air flow, making it hotter than open designs. Gnats seem to like these hats as well.

DPC makes a cowboy/rancher style that is very light, with wide adjustable brim and a lot of mesh for ventilation. And they are relatively inexpensive.

The problem with a sombrero (or any other wide-brimmed hat) is that it does nothing to protect your face from ambient or reflected UV rays, which can be substantial on sunny days or on snow/ice/water. I use an OR Sunrunner, too. It takes a little getting used to, and it looks dorky as hell, but it works.

I'll throw this option out there because I love my Tilley Airflo. Tilley has the LTM6C an Airflo hat with roll out neck protector. Rolls up into the brim when not needed. Certainly not as much face protection as the OR sunrunner, but FWIW, less dorky.

Coolibar makes some decent sun protection clothing too.
http://www.coolibar.com/02511.html or the similar http://www.coolibar.com/02512.html
or
http://www.coolibar.com/02534.html <–more of a regular hat with face/neck drape

Wow thanks everybody for the suggestions; keep 'em coming. I'll start going to these sites now. I agree about the reflected/ambient sunlight, especially in the Sierras, so some sort of drape style hat looks necessary. Dorky and hot I can live with.

added a bit later: looks like it's between the OR Sunrunner and the Sunprecaution hats. I like the longer brim on the Sunprecaution. Sunrunner gets great marks for coolness (i.e. not too hot.) Any thoughts?

OR Sunrunner, far and away the best. It could be improved upon though. I'd like to see one with a second set of snaps further forward for more face coverage, a more breathable top, and fabrics (wool?) that don't stink as much. The last item would be tough, but I'd really like to see the first two happen.