I suspect Southbank (actually South Brisbane)
or some other area near the city centre would be perfect. Do you know exactly where you're working? Brisbane is actually only what we would call the downtown area, so you'd be right in the city if you were working in Brisbane. Everywhere else goes by the suburb name.
So given what you wrote I think Southbank would be great. It right across from the city and you can visit the man made beach at Southbank parklands for free. There really aren't any beaches in Brisbane as it's sheltered from the island east of it. Most of the beaches are about 1 hour north or south of Brisbane.
You can check out the suburbs around the city here:
www.whereis.com.auHere's the link for South Brisbane (Southbank).
http://www.ourbrisbane.com/suburbs/south-brisbaneYou can check out all the other suburbs as well on that site.
Really anything close to the city would be fairly good location wise for work, but I don't know how vibrant the night life is.
For housing/rental costs check out:
www.realestate.com.auThere's tabs at the top for buying, renting or sharing.