I'm curious what aspects you use the Expression Web for and what you prefer to do in Visual Studio.
I understand Expression Blend is for making GUI elements of WPF applications, with the programming done in Visual Studio, but how do Expression Web and Visual Studio fit together?
Expression Web is used for the UI design.
Visual Studio is used for programming the underlying model and hooking up to the UI.
They both understand XAML and can share the project/solution structure.
In fact, the were designed to inter-operate in this manner.