You boys should have a great time down in for the long weekend! There's plenty of options about city & Glenelg to enjoy the Adelaide nightlife. You've picked the perfect time of year to come to Adelaide, with the Fringe Festival on, really getting the place buzzing.
For the Friday / Saturday night I would probably head into the city. There will be plenty of things happening, Rundle Street is probably your best bet, with a selection of great pubs on offer. Be sure to check out the Garden of Unearthly Delights at the bottom of Rundle Street, great fun!
Sunday you could head to Glenelg for a Sunday-session, plenty of good options, particularly on Moseley Square, including The Dublin, The Grand, and the Jetty Hotel.
Enjoy your stay!!
Ben.