There is one unstated, but understandable, policy if you do this: your Gift of Time will be applied to the least expensive hotel.
This trip was my first Tauck trip and it was fabulous! I arrived a day early in Vilnius because there were sights I wanted to see that were not included on the Tauck program. I was very interested in exploring the Jewish heritage of Vilnius and arranged for a private guide prior to my departure. I met 2 couples on the tour while waiting for the Tauck transport to the hotel and they ended up joining me on this tour. It was superb. It was a wonderful way to begin our adventure. I would suggest researching the sites of Vilnius that may not be included on the tour and perhaps use your extra day to explore independently and adapt to the time change.
By the end of the trip, I was ready to go home. Tauck truly does a fantastic job of exploring Moscow. On our last day, we had a free afternoon to explore, pack, shop, etc. Since I knew I was not staying in in Moscow,I did not research additional sites. However, there is always something to do and see! And an extra day in Moscow would have been wonderful too!!
Have a great trip!!