I would look at it this way. The base price for a DONE4 ex-Norway at the moment is £4480. Let's assume the added taxes and fees (and note the taxes aren't the issue, it's the supplemental fees charged by the airlines that makes the big difference) add, say, £1200 to that price, for a total of £5680. If you use all 16 of the available segments, that equates to an average cost of £355 per flight. Now that's terrific value on something like HKG-YVR or DFW-DOH, but not so great on KUL-SIN, which you can fly for £25 in economy or £145 in business class as a walk-up. Of course, there may be cases where there aren't cheap alternatives to using a coupon from the RTW, but with all the time you have to plan, I'd suggest thinking about maximizing the value of the RTW, both in terms of the savings, as it were, by using the RTW over conventional tickets, and in terms of possible elite status ramifications. Your current plan (above) would generate around 1080 BA tier points by my calculations, more than enough for BA Silver but 420 short of Gold (never mind the BA-metal segments required for the moment.) I think it's entirely possible to hit that 1500 with your RTW ticket, if that's of interest to you.

Another consideration is the order of your visits. I'd personally be concerned about your ability to find someone - either an airline operative or a travel agent - who could machete his/her way through the thicket of rules and regulations in order to ticket a route that goes Europe/ME - Asia (with stopovers) - Australia - Asia (with stopovers) - North America. The rule that allows two entries into Asia without the requirement that one of them only be for a "direct connection" to/from the Southwest Pacific is quite recent, and even though you might have the rules on your side, resistance on the part of an issuing airline (blame ignorance of the rules, inexperienced staff, whatever) could make your life miserable. Is it mandatory for you to visit SE Asia en route to Australia, then access North America via HKG or Tokyo? Could you bundle all of your Asia stops separately from the Australian ones, maybe doing Australia first?

If tier points are important, then adding stops in North America is an easy way to run up the score. While the rules only allow one transcontinental nonstop, there are a number of routes with segments above 2000 miles, elevating the tier point totals from 40 TP to 120 TP. For example, Chicago to Anchorage is over 2800 miles each way, Dallas to Anchorage is over 3000 miles, and Dallas to San Juan, Puerto Rico is over 2000 miles, all of which are allowed within the rules.

For example, this route - OSL-DOH-SYD-DRW//ADL-KUL-HND-DFW-ANC-ORD-SJU-DFW-SEA-DOH-MAN-HEL-OSL would generate around 1500 tier points, enough for Gold, including a stopover in Manchester if you want it. With this plan, you'd do your SE Asia shuttling on your own dime, outside the RTW rules, and save the RTW segments for higher tier point or Avios yields. Just a thought, anyway.