As a Marine, I take my footwear very seriously. We are somewhat limited in our choices, as they have to meet a very stringent guideline, but I can say that the best boots I've ever put on my feet are the Bates Durashock sole combat boots. I bought my first pair (black, tropical) when I was a DOD contractor and then wore them as a cop. 12-18 hour days walking patrols and never got foot fatigue. I figured, it's the Navy Seals issue boot, it must be good. It is. You can expect a good 3-5 years of hard use before you see too much wear on the soles.
The Marine Corps now has the same boot in the desert colored suede. Fantastic. For something with a little more aggressive tread (for out in the woods or rough trails) go with the Wolverine model.
Look around a bit. Retail is usually in the $100-150 range, but you can find them NIB at surplus stores for half that.
Navy Seal boot
Footwear | 8" Tropical SEALS DuraShocks® Boot
Marine Corps Lightweight "Garrison" Boot
Footwear | USMC Lightweight DuraShocks® Boot
Bates "Wolverine" Combat Boot
Footwear | 8" DuraShocks® Desert Boot
If money REALLY isn't an issue, for the newest technology, you might try out the Bates Tora Bora. This is a true expeditionary boot, rated for wear in both alpine and desert environments. It's the newest issue for our special operators in Afghanistan. Supposedly impervious to the roughest imaginable use. I've heard good things from some guys.
Footwear | Tora Bora Alpine Boot
Happy hunting!
Semper Fi