Yeah, chridd's concern is part of my issue, too. I like to work with different apps side-by-side, particularly with snapping tiling, and that particular style of application-centric switching just doesn't really work with that. I do make quite a bit of use of (work)spaces, but I still might have four windows on a screen, and one might be maximized - so I'd have to think which apps are which before raising all windows of one application. I do like OSX-style docks over the older-Windows-style taskbars - particularly if they avoid the above problem by making apps with multiple windows trigger an Exposé effect instead of raising all windows of that app.
But yeah, I've preferred just using exposé and Alt+Tab for my main window switching. In the old window manager, Compiz, I had it set up so that batting the upper-left corner with the cursor spread the windows for the current workspace, and it got to be a reflex. Now in Gnome Shell, there isn't really a task list of any kind (there's a "Favorites Bar", but it's ... different) and I'm content to stick with Exposé, which is really nicely handled in Shell (coincidentally a lot like Lion's, which was released later.) It doesn't hurt that they used the same hotcorner I was already trained to. = D
I'd probably need all of that a bit less if tabs in most of the apps I work with weren't more trouble than they're worth; only Chrome really gets them right. (Tabs can tear off and snap back in, a window with no remaining tabs is destroyed, Ctrl+Tab switches tabs, etc.) Again, I don't like having to think about the application while I'm navigating the desktop, and practically any other application will have Ctrl+Tab, but not tearing off, or tearing off, but not snapping back in, and so on. I still use separate browser windows even if it's not a side-by-side situation, though, if I have more than, say, five tabs in a browser. (Just to sort everything out.)
~ I know I shouldn't use tildes for decoration, but they always make me feel at home. ~