My funniest memory of Государственная Третьяковская Галерея was that there was some non-Russian speaking woman from Texas who insisted that the non-English speaking sales clerk accept dollars for payment. They kept arguing, in their respective languages, until the Texan decided it would be a good idea to just walk away with the postcards she was going to buy. That went over well...it ended with her slamming down the cards and the Russian very pissed off generally...
But you're right; there is some incredible artwork there -- I still slightly prefer the Госсударственный Русский Музей in Spb.