Thanks for all the help... not only do we end up saving quite a bit by starting from CPT, but tack on around 8k miles with the revised routing (including IPC). Just need to sort out where we really want to go in Asia, and I think we'll be set.

Also, can I just confirm that we will indeed be able to change/reissue paper tickets after June as long as we ticket by then?
We'd probably just use Jan/Feb dates and then move them back to May once we get to August. Also not sure whether I need to wait until we can change the whole trip or can do a leg at a time.