You can setup specific applications to open on specific Spaces. And all I need to do to switch between them is just the application in the dock, and it brings the focus to that Space I haven't used Expose once since I started using Spaces properly. Also eliminates the need for multiple monitors. Spaces sucks unless you can set the application to always use that Space though, which is what Apple butchered in Lion.
Mail has its own Space, VNC has its one Space, iTunes has its own space. The three applications I use that require the most desktop real estate. Then I have Firefox, Adium, and pretty much all other applications set to the first Space.
So I tried spaces the way that you use it, and i really like that i can put certain apps in certain spaces. I like the fact that you can click that app on the dock and it takes you to that spaces. It turns out this functionality is also in lion. You just right click the app and you can assign it to a space and by clicking that app on the dock it goes to the space. anyways just thought i would let you know.