In addition to Reger, Mendelssohn and Wagner, I also performed two pieces by Bach in my concert on the Sauer organ at Berlin's Cathedral. The 'romantic' arrangements by Reger and Liszt respectively worked really well, in particular the Prelude BWV 867, which showed off the subtle nuances of the many soft 8' stops.
Pictures of the organ, the cathedral, and the stunning view from the dome are available here.
Bach/Reger - Prelude & Fugue in b flat minor, BWV 867
Bach/Liszt - Introduction & Fugue, BWV 21