In Victoria it will take you six years all up if you do law post-grad. It'll take an undergrad 5 years to get their double-degree, provided that they don't fail though.You don't need to couple it with anything. Do an arts degree, then do some postgraduate study. Takes as long as a law degree, and law is a big slog if you have no interest in being a lawyer.
Christ, it shits me that law courses are full of kids who did well at school, but are only doing the degree just because it makes them 'more employable". It just drives up the entrance mark for people who would genuinely like to practice law, but didn't get the prohibitively high ENTER score.
In terms of general intellectual skills, you won't get anything from law that you can't get from an arts degree. Employers who treat a law degree as some hoop to be jumped through, or as proof of intelligence, deserve a bullet.
Disclaimer: I am not a lawyer, nor an arts graduate.
Also have to massively disagree with your last comment. Law is significantly more challenging than your standard Arts subject. It also hones your analytical skills, whereas you can get away with doing nothing in Arts. With that said, law is so unedifying compared to a subject like Anthropology which really tells you something about life and living.
It's a real shame that so many people do law because they don't know what else to do though. Also far too many private school flogs in the course.