If your after gold/plat cards with insurance etc just check the PDS very carefully that the cover is ok for you. Insurance can often look good but you must read the fine print.
Only other thing i could say is....
Amex + Visa/Mastercard seems like a popular conbination, 2 cards is enough for most people.
Make sure your getting the newer microchipped cards,... i think that will be important soon. I know some places already that prefer them due to fraud reasons.
If you want to do an 'dodgy' purchases on-line etc then consider the pre-paid visa cards you can get in Australia, they work as expected.
E