The shortest way in to Lithuania from Poland is in to the city of Kaunas in Lithuania. Vilnius is actually out of the way to the East unless you specifically want to see it. In Kaunas you will be impressed. The Old Town is a marvel and the 1 km long mall that is attached to it is an oasis of modern trendy shops in the middle of nowhere. The place to stay is http://kaunas.lcn.lt/sveciunamai/en/about.html direct website www.sveciunamai.lt