My brother is completing a Melbourne Uni degree and is loving it.
What he likes about the Melbourne degrees is it now gives you more opportunities to try new things and is more flexible.
He started off at the Bachelor of Science (planning to major in chemical engineering) and was completing Breadth in Economics. However, he discovered he loved Economics and swung across into commerce. Now he is planning to either complete Masters in Engineering, honours in Economics or honours in finance.
The thing is if you are unsure what degree you want to do: Architecture, commerce, accounting perhaps Melbourne uni model would really suit you because you could not only experience commerce but complete breadth in environments or vise-versa. And if you discover which one you like better you can always transfer.
I believe it varies on what percentage they take in for honours and masters and getting in depends on your results:
I believe for finance honours they only take 30 people and it is really competitive. Therefore, you need to get results in the high 80s in third year for Finance (I think!) However, if you get into this, you are well on your way for an awesome career. These people start on wages of about $100000 and it just keeps going up, however they work like 80 hours a week.
Honours in Economics you need over 70%.
Masters in Engineering ( I know its not relevant to you but it may be a good indicator) 65%
I suppose the one down side would be that law is post graduate, if you get a result in the high 90s and can get into Commerce/law at Monash you'll have to really make sure law is for you because it would probably make your life alot easier at uni being in law straight away, rather than having to work your arse off to make sure you get into the post-graduate law at Melbourne uni. When I went to the open day at Melbourne Uni, Melbourne Law sounded extremely competitive and very expensive!! (only about 50% of people get hecs for law)
Hope this helps and good luck with your choice