There was also a most similar post not that long ago-just scroll down. It showed current timings for train-bus-walk-bus-train ´connections´ from Vilnius to Riga.
To be honest-and this does not include the hopefully better to come arrangement for LIT-LV: for normal not so much ´I want it all by train as much as can´ people the direct bus is by far the best choice-also without all those worries about prebooking or supplemts-though in fact as all listed trains are purely local, the idea that any faraway train should be booked on the fone monthes ahead cannot even be done over there. An InterRail is also a waste of money, local fares are lower-unless you have a very long term one and use it in high fare countries a lot to get its worth out.
Have done it myself when one even still needed a visa to enter-pay 50 DEM, but valid in all 3, and the whole railsystem was very much Soviet-style with the classic overnite kupeyny/platskart trains/poiezd between the capitals. That did not last very long since.
As for that Soviet/Russky enclave: there simply are no connections into there for you available, so no worries. There remains a corridor train for the Russky.
