My husband, Andy Dunaway, and I enjoy the 5.11 Tactical line of pants. They have been around for 30+ years and are used mostly by law enforcement, EMS and FBI among others. Though they weren't designed for photographers, they certainly are a great fit! They are made of durable material and have lots of pockets. One other perk is the the large belt loops, which will allow you the option to use a camera belt and drop pouch system like the one Kata has. You need a nice, solid, thick belt that can distribute and hold the weight evenly around your waste. Check out the Rigger's Belt by Spec-Ops. There are six color options and has up to 8,000 pound tensile strength. You can't go wrong.
As far as shirts are concerned, I believe collared shirts look the most professional. When I'm working and moving around lighting gear, I do work up a sweat. Therefore, wearing a stiffly starched dress shirt isn't an option. Both Andy and I wear Columbia sportswear. They have a men's and women's line that will keep you cool and looking professional. I like the various color and style options they offer.
Lastly, I'd like to talk about shooter's vest and jackets. Traditionally, the first thing that comes to mind is a fly fisherman in the river casting his line and wearing a khaki vest and floppy hat. Well that's not my idea of fashion forward. Recently, Manfrotto released a new line of vests and jackets designed with the photographer in mind and I'm a HUGE fan. The soft shell jacket in particular is wind resistant and has a seamed sealed water proof design. The pockets are large enough to stuff whatever gear you want for a shoot on the fly.
The a part of being a professional photographer is dressing professional. Walking the fine line between fashion and function can be tough. I hope this blog helps a bit. I'll keep y'all posted as new clothes and such hit the shelves!