I am a regular QF domestic traveller and use Qantas T1 Valet Parking every time. The daily rate is $5 more than the daily rate at the airport carpark opposite. That is a small price to pay for convenience and great service (and less chance of bumps). The staff are friendly and efficient (it helps being a Qantas frequent flyer). QF provides a check in service there as well, and I have found the check in to be quick, efficient and able to make changes without fuss.
Cheaper options, such as the long-term carpark exist, but for the length of stay (usually only 2-3 days), convenience and a lot less than the return taxi ride home-airport-home, I find this hard to beat!
Self Park
Valet
Car Wash