Group a series of buttons together on a single line with the button group, and super-power them with JavaScript.
Instead of applying button sizing classes to every button in a group, just add .btn-group-* to each .btn-group, including each one when nesting multiple groups.
Place a .btn-group within another .btn-group when you want dropdown menus mixed with a series of buttons.
Make a set of buttons appear vertically stacked rather than horizontally. Split button dropdowns are not supported here.