James-
I'm sorry you've had to wait so long for a reply. But when it comes to backpacks, I'm your man. I have used a ton and used them in all kinds of conditions - from pouring rain, to blowing desert dirt, to well below freezing. And I have a Dryzone backpack and cannot - I repeat - cannot recommend it. Although my Dryzone pack served me well and is responsible for some great photos, the waterproof zippers are a huge pain in the butt. Mine doesn't work at all anymore. I cannot zip the camera compartment closed.

I don't know what your budget is like or how much stuff you have to carry. But take a look at my review for the Lowepro Vertex backpack. I really like it. The harness system fits me really well and it carries a lot of equipment comfortably. I also like the high-end Tamrac backpack cases. I used one as my main bag for years.

Don't worry too much about water. For one, I've had all my gear completely soaked and I've yet to have anything really fail. The best thing is to have a pack with a rain cover. That will do the job. Waterproof is only for the very few who are actually rafting or swimming with their gear. I am out in the weather all the time and I don't worry about it.

Hope that helps. Let us know if you have more questions.