I'm probably spending a couple of days in Riga, Latvia in April. I may also pass through Vilnius, Lithuania. I speak not a word of Latvian or Lithuanian, but I'm conversant in Russian. I also understand that linguistic nationalism has been a major part of the statecraft of post-independence governments all over the Baltic region--the Latvian government, for example, recently increased fines for teachers (including Russian language teachers) who score poorly on Latvian proficiency exams. So I'm guessing, hopefully incorrectly, that there's a fair degree of resentment of Russian among non-Russian citizens of these countries.
My questions are these: is it safe to assume that someone on the street in Riga will speak Russian? I know that both of these countries have large native-Russian populations, and that anybody old enough to have gone to school in the Soviet days will have been required to learn and use Russian. So I assume that anyone over about 30 will know at least SOME Russian. But would people rather not use it? Am I better off using English nowadays?
Assuming Russian will be useful, what would be a polite way to say, "Sorry, I don't speak [Latvian/Lithuanian]. Do you speak Russian?" I know I could just ask in Russian straight out, but I'd like to at least make a respectful gesture in the indigenous direction.