Transportation

A few helpful references:
~Eurail Planning Tool
~Bing Travel
~Eurail Railway Map

Flights and estimated travel times:

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Part 1: Russia and Finland
San Diego > Moscow [~19:00, one connection]
Moscow > St Petersburg  [1:10]
St Petersburg > Helsinki [1:15]

Part 2:
Itinerary #1: Baltic states
Helsinki > Tallinn [0:35]
Tallinn > Riga [0:50]
Riga > Vilnius [0:50]
Vilnius > San Diego [~22:00, two connections]

Itinerary #2: Scandinavia
Helsinki > Stockholm [0:55]
Stockholm > Gothenburg [1:00]
Gothenburg > Oslo [1:00]
Oslo > Bergen [0:55]
Bergen > Copenhagen [1:20]
Copenhagen > San Diego [~17:00, one connection]
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NOTES:
~For Itinerary #1, Vilnius would be the final city, and it takes a full day to fly back to San Diego. As a result, July 14th (Saturday) will need to be the travel day in order to be able to return to work Monday morning. Itinerary #2 finishes in Copenhagen, which will result in a sufficiently shorter return flight home. Thus, the reason Itinerary #2 ends a day later than #1.
~Use of rail within Sweden and Norway may be worthwhile for views of countryside and fjords, and may be comparable in total transport time taken (due to airport add-on time). Above travel times are only for air travel, not train.