I'm not clear if you actually need the flexibility on the flights or not, or if flying on ANA is of any benefit to you. If I had a stack of avios, no need for TPs and was absolutely going to fly on my booked dates I'd probably just spend the avios.

Flying down worked quite well for us on a 10 day visit as it meant we could fly down and be able to use a 7 day JR pass for the remainder of our trip.