See if there are any direct flights in your city, Moscow or St. Petersburg. If so, you can choose one in and one out. If not, you can divide it into 223 and try their train in the middle.
Personally, I prefer Moscow, especially Red Square. When I have the opportunity to live in the surrounding area, I can see the different scenery in the morning and evening, especially at night.
St Petersburg is mostly a palace, especially suitable if you like art and culture.
Day and night on the Red Square, totally different scenery.
There is a presidential cabin restaurant in St. Petersburg, which is not expensive, but I think I like their sense of ceremony very much. Russians like red vegetable soup very much. We can try it.