Thanks all, appreciate the feedback!
At this stage I am committed to Singapore. It's home. I've been here almost 10 years and am now a permanent resident. The eventual plan is to move back to Australia as it's too expensive to retire here, but I see myself staying here a good number of years yet. I looked at returning back to Australia a couple of years ago but it would have meant less pay, no annual bonus and much higher tax, so it works out better for me where I am. Australia's capital cities aren't cheap any more despite the infrastructure being somewhat lacking.
I didn't really aim to come here to earn a lot, it was more a life experience. I had friends who had taught English in Japan, backpacked through Europe - this was my little 'adventure'. I originally thought I'd stay for a year or two, but I've come to like it. I don't own a car and keep my expenses low compared to most expats. I'm also lucky that Singapore is a hub where many companies set up their head offices for the Asia Pacific region, so there are more job opportunities here.
I haven't done the math yet on how much I need and how quickly I can get there, primarily because living overseas adds another level of complication. For me to invest in Vanguard index funds the costs would be higher trying to access those investments from outside the US. I'd like to put some money into property back in Australia but since I'm not a tax resident there I miss out on a lot of benefits. Singapore is great in as much as there is no tax on capital gains, but property doesn't make a great investment here due to the high entry cost and government legislation aimed at curbing speculation. The local stock market doesn't offer the same returns as the US either.