I love i3 for being super-light-weight and super-productive, I love GNOME for being pretty and making all the funky bits of my laptop Just Work, and I wish there was a way to make them play nice together.

I still haven't found one, but I came across a gnome-shell extension called ShellTile, which lets me easily group windows side-by-side, subdivide them and resize the inner borders... a bit like panes in tmux. It doesn't have any of the keyboard shortcuts of i3 and doesn't make GNOME any lighter-weight, but it might be a nice way for GNOME users to try out the idea of a tiling WM without going all the way.