I am thinking of doing the same thing for my parents, but one reason why I'm planning on using miles is because you can't use SWUs on non-AA metal (am I correct on this?). By using miles, you can get them on other OW planes which greatly expands your list of destinations, especially in Asia. I found that awards were similarly priced for both AA and non-AA metal (on the AA.com site).

This also comes with a nice side benefit. I now have a reasonable explanation to give my brothers as to why I'm doing crazy MRs all over the country My parents don't know yet. It's going to be a surprise.