I've always loved tiling WMs on big screens, since it's a really efficient way to use all of that screen real estate. i3 really comes into its own on my multimonitor desktop setup. I've just never felt any real gain on anything smaller than 17". On my 13" macbook air, however, I find that as soon as I split the screen 50-50 neither window really has enough space to be comfortable. (I've tried using Amethyst[1], but that's all)