Do I use anything else? Hell Yes! Weather resistant does not mean water proof, and my gear is not cheap.
1. First line of defense is I don't go out in the rain with my camera in general. Sure if there is something worth shooting, like for example I'm getting paid, or the big foot convention is in town. But I don't go outside in the rain for no reason. Why? Seriously what are you going to shoot? I sell stock photography, and there is little call for the rainy drab photo of ____. What a great day for post processing!
2. I use LowePro all weather (AW) Bags. My main bag actually has 2 rain covers, one for the top for light rain, and one that covers the whole bag. Both fold up into pockets. I also keep a trash bag inside to bag up a camera on tripod, convert to a poncho, or ultra-secure my bag if in a small boat or something. ( a .$50 trash bag is cheap insurance)
3. Pelican cases. When i shoot pro surfing, or some similar event that gets me in the sand, I love my pelican cases. They can be seats on the beach, and when you get home, you wash the outside with a hose.