We just got back from a trip to Lithuania/Latvia over Easter. We spent a quick three days between Vilnius and Riga. In Vilnius, the taxi from the airport to the Scandic hotel (not in the Old town, but within walking distance) was 35, on the way back it was about 25 (radio dispatched taxi), so calling ahead does seem to be cheaper.

We did a Vilnius city tour our first afternoon, then the next day hired a car and drove to Riga via Trakai and Siauliai. The roads were in excellent condition.