Looking for The Perfect Camera Bag for Day-to-Day use

I currently use the Lowepro Slingshot 100 as my day-to-day camera bag.
There are many things I like about it. It's small, easy to access as I
can swing the bag quickly to the front and has some really useful
features like a waterproof cover so that I can cover the bag in case it
rains. But there are a couple of downsides. For one, the bag is
extremely uncomfortable to wear for long periods of time. It would also
be nice to be able to carry a tri-pod as well. My Gitzo doesn't come
with a sling.

So, the perfect camera bag for day-to-day use would have the following features:
* interchangeable slings between my right and left shoulder so I could distribute the weight
* means to carry my tripod
* ability to carry a water bottle
* space to carry miscellaneous stuff like manuals and sunglasses
* comfortable to wear for at least 5 or 6 hours a da