I'll start you off with two 20th Century music discs, both from Reference Recordings with Oue and the Minnesota Orchestra, Bernstein's Candide and other pieces and Copland's Third Symphony. Quite frankly, anything from Mephisto and Company onwards from Reference with the Minnesota Orchestra will give you some of the best sound you'll ever hear on CD, and while you may find Oue's tempi a little slow, still satisfying performances. Also the Adams/Glass and Rosza violin concerto discs on Telarc are superb performances and recordings. Also check out Harmonia Mundi recordings produced by Robina Young, always well-recorded and played--the recordings with McGeagan and the Philharmonia Baroque, such as the Corelli Concerti Grossi and Handel Arias for Cuzonni, are exceptionally natural even though comparatively older recordings. Finally, while it is not the definitive performance, the Delos recording of the Mahler 2nd with Litton and the Dallas Symphony is probably one of the best full-scale orchestral recordings you'll hear of that piece (and even better on SACD). There are many more, but I'll leave them to others for now.