> The things that I don't feel as comfortable with are basically UI things and application launching. I love Cmd-space to launch stuff on OSX, and hitting the Windows key to search for stuff to launch just feels sluggish in comparison.

In Gnome, Hit the Windows key and start typing 'shortcut' to run the keyboard shortcut editor.

Start typing 'application' to search-ahead-find the 'Show all applications' shortcut and click it.

Press Cmd-space.