Spaces has been central to how I've been using my mac since it became available. In recent years, it's basically been setup like this:
Space 1: My main desktop. Most basic apps that I don't need fullscreen (messages, notes, finder, utilities, etc, etc) are set to open here. I also use a small tool called 'Quitter' which lets me set many of those apps to quit or hide after a set time of inactivity, so after I've been using a different space for a while, when I go back to my my 'main desktop' it will most often be empty and tidy.
Space 2: My browser in fullscreen, with a few standard tabs; news, google mail inbox, often used forums, etc. Basic browsing essentially.
Space 3: My browser in fullscreen with a few tabs of streaming feeds of sports, news etc. My "TV", basically.
Space 4: most often used for Adobe Lightroom, Avid Pro Tools, and similar 'big' apps.
This is just a basic starting point, of course, I rearrange and customize spaces all the time, and move quickly between them with a two-finger swipe. But I find if I let the number of spaces grow, it quickly loses its practicality.
Option-rightarrow/leftarrow: takes me to the next space/previous space.
In fullscreen browser spaces; cmd-2-3-4... moves between tabs. A two-finger tap on the magic mouse takes me to 'mission control' (F3) to rearrange spaces.
I have two displays, cmd-F1 switches between each display with its own spaces, and both displays 'mirrored'. It's also very easy to drag one space from one display to the other.
I love Spaces.