These would be my choices:
Peterhof Palace and St. Petersburg - 9 Hours AM $175.00
Moscow By Air - 14 Hours AM $599.00 PREBOOK ONLY
Treasures of the Hermitage - 3½ Hours AM $60.00
Peterhof Palace - 3¾ Hours PM $81.00
(hopefully these aren't at the same time)
Moscow wasn't offered on my cruise; neither was the ballet. I did enjoy the Spectacular Evening at the Yusupov Palace. I don't remember it being that pricey. Part of it is a medley of opera arias.
Did I spend enough of your money?
Shopping is possible everywhere, so definitely don't waste your time doing that. Too many other great things to see.