All of the alliance-based RTW products (Oneworld, Star and Skyteam) are very rules-intensive, particularly with respect to routing conventions. In the case of Oneworld (which most of us feel is the best product line) the two RTW products - the Oneworld Explorer (continent-based) and the Global Explorer (mileage-based) limit the number of flights you can take in any one continent - four for all except six for North America. Your Asia plans would involve five or six flights (or more) and thus would be ineligible.

As christep says, you could easily break away from the RTW in some city like Singapore, Bangkok or KL and use LCC or separately bought flights to bounce around the region, then resume the RTW and use the remaining RTW segments as you choose. That of course would add to the cost of the overall trip.

Now the Star Alliance RTW products don't have as many restrictions on the number of flights you can take in a given region (although all alliance RTWs are limited to 16 flights total.) So your SE Asia plans could probably work using various Star members (Star is much more well represented in Asia than Oneworld.) However, Star's RTW products are mileage-limited, and are generally considerably more expensive than Oneworld's.

And here another very important aspect of RTW travel comes into play. RTW tickets are priced differently depending on where the trip starts and ends. For example, a three-continent business class Oneworld Explorer (which is what you'd need - North America, Europe and Asia) starting and ending in the USA costs $9699 before taxes and airline fees. The same ticket starting in Canada costs $7830, in Dublin $7168 and in Oslo $6213. Can you get from Washington to Oslo and back for $3300? (All in USD by the way.)

Star Alliance RTWs cost more from most countries. A 29,000 mile business class *A ticket starting in the US comes in at $10,360, from Canada $8280 and $7672 from Ireland or most of the Euro countries.

So in either scenario you'd save a lot of money buying and starting the ticket in Canada instead of the US. While the Canadian Star trip would allow you to hit most of your Asia targets, the $450 difference in base price might get washed by fares you could find with LCCs using the Oneworld ticket. And with a maximum of 29,000 miles (the cheapest tier) you'd pretty well use up all your eligible miles by the time you got back to the origin point.

But by limiting the number of Asia flights with the Oneworld ticket (due to the rules) you'd end up with many more flights available in the overall ticket. These could be used within North America following the end of the Asian part of the trip. Oneworld limits you to two stopovers within the continent of origin, so if you wanted to optimize the possibilities for using the ticket within NA, you'd have to buy it somewhere else.

But that might be worth it. Say you bought a ticket originating in Norway, then flew a route like this - OSL-LHR-SIN-KUL-CGK-HKG-PEK-DFW-IAD and then took a break. Then, up to months later, used the ticket for some domestic travel, then ended up back in Norway within 12 months of the first flight, something like this - IAD-MIA-IAD-DFW-LAX-IAD-LHR-OSL. That would give you significant domestic travel on the one ticket, which would probably more than offset the cost differential of the additional tickets in Asia and/or the additional cost of flying with Star Alliance instead.

Lots of information here, maybe confusing, but there's good value in these products once you get the hang of it, and relate RTW tickets to a broader travel plan than just one trip.