combining compiz with LXDE or something like that, sounds like a reasonable way of switching between window clusters/virtual desktops in a pleasant way.
That's probably your best bet. Compiz lets you use keyboard commands to manually re-tile windows, move them between workspaces, toggle them as "always on top", display them on multiple workspaces at once, drag things onto other workspaces using the flip cube, force full-screen for a particular workspace, etc. A lot of people dismiss Compiz as mere window dressing, but it's real advantage is the incredible amount of control it gives you. It also adds smooth transition effects to LXDE, which I think improves the sense of "flow" and makes the interface seem snappy.
Knoppix has an fairly good out-of-the-box LXDE/compiz setup that you can try (you'll want to turn off some of the obnoxious animations). You also might want to consider Gnome 2, XFCE, or Mate as a desktop environment (along with Compiz, of course).
Also food for thought: a tiling window manager.
Awesome is what I use on a laptop, and it is designed around strong multi-workspace support and space utilization. There are
lots of these kinds of window managers, and I found them very useful for doing
real work on a small screen.
I suppose some people will recommend KDE, but I always felt like it got in the way of what I was doing. For what it's worth, it has fairly good multi-desktop support once you set up some hotkeys. I always used ctrl+alt+# to switch to workspace #, and alt+shift+# to move the current window to that workspace. I usually used 9 workspaces (this was back in college, all the lab computers used SUSE), and set up the mouse so I could "push" it against the edges to switch between them, but nowadays I like the 4-sided cube approach more).
E17 is pretty good, I used it for a couple months on my lab computer. It's ridiculously fast, but is also... "quirky". Try
http://bodhilinux.com/And of course, toy interfaces need not enter the discussion.
