Well, the point of breadth is to do something that you're interested in but is not covered by the bounds of your degree.
There's a few ways to go about it:
a) Use breadth slots to enrol in subjects that you feel will help you professionally down the road (e.g. you often see engineering students enrol in commerce subjects such as micro/macro economics. Languages are another good example.)
b) Use breadth slots to enrol in subjects that are completely off base from your own course but that you enjoy and/or are a bit of a "bird course" as Canadians would say (e.g. music, film, history, literature etc.)
For me, I've taken option B for a few reasons. First, as I'm majoring in Civil Eng through the Environments course, two breadth slots are automatically taken up by maths subjects (namely Calc 2 and Linear Algebra). For this reason, I decided to use the remainder of my breath slots for something a bit easier and a bit more of interest to me (though I do like maths). Second, I'm really interested in film, so have chosen to do a few subjects from the SCRN/CULS fields. Thirdly, I love to write and am a pretty good essay writer, so these subjects are pretty easy for me. Lastly, these subjects often have no exams, which lets me concentrate on my core subjects and subsequently get better marks across the board.
(Side note: Girl/Guy ratio is favourable in artsy subjects, especially coming from the cockforest that is engineering)
Obviously, these two approaches are not mutually exclusive. As a science student you may enjoy commerce/languages, as a commerce student you may enjoy science etc. In this case, hugs all round, you get both.
For me, the opportunity to do breadth subjects was a major selling point for Melbourne Uni. If you view them as a chore or a necessary evil, you're probably at the wrong institution.