Thanks all for the replies. Our kids will be 11 and 9 so we don't need to share.

Generally we would prefer two rooms. I don't mind spending up to around U$500 per night for the four of us, but I think this rules out 2 rooms at the FS, Pen, Park Hyatt, etc.

One more factor- we are arriving into Haneda and when we depart we are taking the train to Nozawa Onsen. I don't have a sense of what this means for location or even whether really relevant.

Thanks again for your help!