14 day JR Pass this December

Hello,

My husband and I have 14 day JR passes which we will both activate on 18th December. At this stage we will have been in Tokyo for just under a week, so will have seen a lot of the local sights. On the 18th my husband will use his pass on the Narita Express as he unexpectedly has to return to Singapore for 2 nights for a meeting. He will return to the Shinjuku area using the Narita Express on the 20th December.

I am keen to start using my pass by doing a couple of day trips from the Shinjuku area during the three days my husband is away. Do you have any suggestions that would make good use of my pass? I only want day trips as I have accommodation booked in the Shinjuku area during this time.

The rest of our itinerary is as follows. I would appreciate any feedback or alternative suggestions. With regards to Kyoto, we will be there over the Christmas period. Is everything likely to have shut down for the holiday, or should we still be able to see the sights? Even if things are shut, do you think it would be the best place for us to spend our Christmas?

21 Dec (JR day 4) train to Nagano, visit snow monkeys, o/n in Nagano

22 Dec (JR day 5) train to Takayama, o/n in Takeyama

23 Dec (JR day 6) o/n in Takeyama

24 Dec (JR day 7) train to Kyoto o/n in Kyoto

25 Dec (JR day 8) o/n in Kyoto

26 Dec (JR day 9) o/n in Kyoto

27 Dec (JR day 10) o/n in Kyoto

28 Dec (JR day 11) train to Osaka, o/n in Osaka

29 Dec (JR day 12) o/n in Osaka

30 Dec (JR day 13) train to Tokyo, o/n in Tokyo (Shinagawa area)

31 Dec (JR day 14) Narita Express from Shinagawa to Airport and fly home!

Am I able to reserve seats on trains as soon as I have swapped my exchange order for my pass, or do I need to wait until the first day I activate it? I am aware that we are travelling at peak times and would like the security of seat reservations, particularly for the train back to Tokyo on 30th December.

Thanks in advance for any help/guidance/suggestions with regards to above, Lydia