The combination of the Dock in OS X and Spaces is a powerful one. If you set things up according to this Quick Tip, you can just click on a running app in the Dock, and OS X will whisk you to the Space that contains that app.
Previously, I've written about a nice keyboard shortcut to manually change OS X Spaces quickly. That's optional, but a good tip as well. Also, if you're rusty on OS X Spaces, here's a tutorial.
Even though I use a large Hewlett-Packard display, I still don't have enough room to display all the apps I use in my daily work. And so I use OS X Spaces to partition one set of apps (calendaring, email, World Clock) from PathFinder, browsing, and writing.
If you've set an app to run in a specific Space, as I have, then it's easy to double-click that app in the Dock and be taken quickly to the space that contains that app.
By the way, how does one define which Space an app will run in? Right- click the app in the Dock and select "Options." It looks like this:
Okay, now it's time to get to the good part. You can avoid having to double-click the running app in the dock to jump to the desired Space. Go to System Preferences > Mission Control. Check the box: "When switching to an application, switch to a Space with open windows for the application."
This has the side effect of allowing a single-click on the running app in the Dock to switch to the Space that contains that app. If you have a fast GPU, that jump happens quickly, and it's virtually transparent to your work flow.
I've used this trick every day for years, and it's the easiest, fastest way I know to seamlessly work with my ever-changing apps across multiple OS X Spaces.