RTW tickets earn full BA tier points, at least in business and first (I don't know about coach).

The biggest problems with your proposal are that you are going to paying a per diem for your employees for at least 10 days (likely less than the difference in air fares so shouldn't be a huge issue).

But the bigger issue is that, for work in SE Asia and Australia, it is an awful long way home when you have to fly the rest of the way around the world to get home. Obviously a bigger issue from the west coast than the east coast of the U.S.

RTWs work for me because I have business in SE Asia and Europe so I can schedule it to do on RTWs (at least most of the time).