I would use MAI, GA and Silk Air. There is a direct flight between RGN and REP. This is the grouping of towns that I do and I can't get enough of, I imagine you have set aside time to do Bagan and see if your hotel can get hold of a good guide in Yog, spend time checking out the shrines outside of Bor, so many of the tours do not pay these any attention at all.