Upvote:1
Although I can vouch for how awesome Contiki is, I can understand that the price-point is higher than you'd spend on your own.
As Mark Mayo pointed out, it's really easy to find where the party is at in Australia. Nearly all of the top-rated hostels found on HostelWorld will be a party with a bar and sometimes a club. I stayed at Base Hostel in Melbourne and the place was pretty crazy every day of the week. If bunk-beds are not your thing, most of these hostels have private rooms as well which might be more convenient for bringing in "guests".