I want to use a tiling window manager with my dual monitor setup, but almost all wms seem to treat each monitor as an independent workspace. This means that I can change the workspace of monitor 0 without affecting the workspace of monitor 1.

This is not what I want -- I want a workspace to span both monitors, where each monitor is essentially a separate column for tiling (my monitors are oriented vertically, so they are well-suited as tiling columns). When I switch workspaces, say with Mod-[0-9], I want both monitors to change contents.

So far the only wm I have found to support this is wmii, but I'd love to try some other options. Have I missed this capability from other tiling wms?