I now have a multitool (Parks I-beam model) with a chain break. I only carry the adjustable (6" just works on pedals) when I'm going to assemble/disassemble at the termini. I carry a cassette tool on longer trips. And a small roll of duct tape, of course.

The bike always has one spare tube, patch kit, multitool, and tire boot. On tour I add another spare tube, spare spokes, a couple of 5 mm cap screws, and a shifter cable.