Tabbing only some windows in i3

Sorry for the noob question. I have recently started using i3, and often I find I need some windows to be tabbed and another window to not be tabbed. Usually I press mod+w, but that puts all of my windows into tabbed mode. I then have to select the window I don't want tabbed and then use shift+mod to move it out of the tabbed view, which feels really inefficient. Sometimes I also wish for two groupings of tabbed windows to present side-by-side, but I can never get it to do that. How can I do this efficiently?