Vilnius and Kaunas both have good air connections within Europe. From the US and beyond, you're likely to change planes in a hub airport such as Amsterdam, Warsaw or Frankfurt.
AirBaltic (www.airbaltic.com) flies to Vilnius from Rīga several times daily and from Tallinn on most days, and also offers scheduled if sporadic service from Rīga to Palanga. These flights are more frequent in summer (May to September). Many travellers arrive via low-cost carrier Ryanair (www.ryanair.com), which operates routes to Vilnius and Kaunas from several European cities.