The dokar is the traditional way to get around, and the horses are generally well cared for. They look like they work hard, but they probably only do one run an hour or so. The becak is interesting but will cost more in Salatiga because the city is hilly. For two people at once, it is good to pay extra because it is heavier. It also depends on how many hills he goes over for you.
Night runs cost a little more.
Once in a while a bus will break down, but usually a minute later you will be on another bus. They don't exactly stop for people getting on and off, they slow down, and the man at the door helps you up or down quickly and off you go. The art of bus travel is fun to perfect, and the amazed Indonesian faces look impressed at your abilities if you get the hang of it. The drivers are sometimes absolutely audacious, and are not afraid of any vehicle unless it is bigger than they are. The population density is high on Java and waiting for a break in traffic takes too long.