With the Southern Expressway you would be OK commuting from Christies Beach (Beach Rd exit) or if you would like more for your rental money - possibly Port Noarlunga South or Seaford - at the end of expressway. It will be under 10 mins more time commuting to CBD, but your dollar would go much further besides you get less undesirable characters you might still encounter at Christies Bch. And much quieter (in case you are not a fan of hustle and bustle).