Credit card rewards are quite valuable to those who are financially savvy and always pay off their cards monthly. The two ways to look at this in Australia are
'earning cards' and
'churning cards'. Basically, some cards are for keeping so you generate few thousand points/year on things you were going to buy anyway, while other cards are for sign-up bonuses (churn cards), where you use the card just enough to get the sign up bonus and then cancel it. The latter group of cards can generate 250-500k points annually and this allows many point-hackers to travel in business/first for less than the cost of economy tickets. However it can be a PITA to sort out the paperwork, book the flights, and monitor your credit score a bit if you also have other loans (i.e. mortgages). Depends on what you want to do with your free time!
Here is some basic information on the benefits of
everyday earn cards for those interested (modified from a group I follow):
Everyday points earning: Usually a combination of Amex (from Amex directly) and a backup Visa or MC will suit most people for generating points through everyday spend. The exceptions are those who only want one card for everything in life. That is easier but will not result in maximum points.
AMEX Cards:AMEX Platinum Explorer. The main "keeper" card, and the card to use if you just want one. It usually earns 1.5ppd everywhere AMEX is accepted (think 1.5 qantas points/dollar, 1.5 velocity points/dollar). Use this for everywhere Amex is accepted except overseas, supermarkets, fuel, or anytime the surcharge is not more than 1% higher than that for visa/mc. Annual fee is mid range, but fully offset by a travel credit as well.
**Note that by itself this card is good, but even better in combination with the below Amex as you can "link" them so that this card earns what are called 'Ascent points'. That changes the earn rate to 2 ppd.
Currently a 60 000 bonus point offer for new sign ups (can't have held an AMEX card from them directly in the last 18 months):
https://goo.gl/oZWjQwAMEX Platinum Edge. This is one of my "keepers". 3ppd at supermarkets, 2ppd on fuel. Much has been written about this card on various blogs. Low annual fee which is fully offset by a travel credit. Transfers to many airlines.
Currently a 10 000 bonus point offer for new signups (can't have held an AMEX card from them directly in the last 18 months):
https://goo.gl/215RyjIf you're going to get an Amex, it's always best to sign up for the Explorer first as the point bonus is much greater. From time to time the point bonus also approaches 100k instead of 60k. That number of points can be exchanged for a business class return trip from Syd-Melb on Japanese Airlines.
Visa/MC options:St George Signature. Mid range fees with great points earn for a Visa. Earns 0.75-0.85 ppd (bonus points after 1 year). This could be a keeper if you have low FX spend and high total spend on CCs as it earns better but has a higher fee. Flexible airline earn but need to choose Qantas or Amplify upfront.
Coles Platinum. Low fee, relatively high earn. Should be your primary card for overseas spending as no international transaction fees. Usually a keeper.
Citi Prestige. This card has been gutted recently. It is another for frequent travellers and suits economy or mid-high end hotel lovers as it comes with lounge access and unlimited pay 3/stay 4 hotel deal. Also comes with some chauffeur transfers. Day to day earn is low 0.4-0.5 to VA and SQ, but earn with hotels and airlines is 1.5ppd. Put through enough $ and they may halve the annual fee.
Virgin High Flyer. One of the best earn Visas with a medium fee. Extra points when paying Virgin Air too. As it has an fx fee and costs $289 it would need to earn 20kish additional points to the Coles MC to justify its place in your wallet.
I would be happy to post more about this if there is interest, a good place to start is:
https://www.pointhacks.com.au/