Am traveling from the United States to St. Petersburg on an award ticket and then back from Moscow next July. Any suggestions for stopovers --

We'd rather do the stopover enroute to LED. We are considering Copenhagen, Helsinki, Prague and Budapest to name a few.

Helsinki was recommended as we could save the stopover and fly to HEL then train to LED and use stopover on way back. Interesting but time is limited.

Any idea how much the train costs in USD. On a Helsinki site I saw a 144,00 price for a first class seat but was not sure in what currency. If Finnish it is under 440 and that seemed cheap.