What are the visa options for an Australian staying in Thailand for two months before heading to Vietnam?

Get the 60 day visa if you are only staying 2 months. It's a little cheaper and saves you the immigration time. You'll spend less time applying for the visa than at immigration I think

As people mentioned.

You can enter Thailand on visa-exempt for 30 days and it's eligible for 30 days tourism extension for 1,900 thb at the local immigration office.

(check the airline policy on your own)

As a rule, you are supposed to have a tourist visa (TR or Single Entry Tourist Visa, SETV) if you plan to stay more than 30 days.

Having SETV gives you:

- 60 day 59 night stay on entry to Thailand, also eligible for an additional 30 days extension

- no need to use a half to one day at the immigration office to apply for an extension

- the official fee for a SETV is cheaper than for an extension

- less hassle at the airport check-in

The decision is yours.

You could buy a visa for 60 days before you come and stop worrying

I've just arrived in Thailand a week today from UK, I was coming to stay longtime getting a retirement visa after the 30 day exempt, flow out from London with Eva nobody asked about onward travel or immigration at Bangkok but that was with Eva. I had the same worries as you so I booked an onward travel ticket that cost me £12, this gives you a flight booking that lasts for 48hrs not that you can use the flight it's just a e-ticket (Google onward travel ticket) hope this helps if you want to contact me personally I will send you the screenshot of the ticket

Get a longer visa before you depart Australia then no worries at all.

yes you can enter visa exempt for 30 days and then extend that for a further 30 days, BUT your air carrier may not let you board if you do not have confirmed travel out of Thailand within the first 30 days