i like penderecki's later "neo-romantic" works as well as the earlier ones. polish requiem is indeed among the best requiems composed in the last 50 years. among the earlier works i like the two string quartets, florescences and de natura sonoris ii. the two violin concertos and the second cello concerto, all of which are among his later works, are probably my favorite works by him - together with the threnody, that is. symphonies nos. 2 and 4, and st luke passion are also very good.
i don't know any recordings of pittsburgh overture on the market. i taped it from the radio about 8 years ago.