From what I understand, you can't have a G-A trill key when you have a C# trill key. I guess this is because of the spacing required to fit both tone holes next to the Thumb Key. I think it's an either/or mechanism. I have played a G-A trill flute before, but to tell the truth I would use it far less than I use the C# trill key.
As far as pieces go: some pieces that are more fluid sound with the C# trill are:
1. Ibert Concerto - 1st Mvt. - C-Db trill third and fourth lines from the bottom
2nd Mvt. - Stable High Ab at Reh. #31
3rd Mvt. - all the tremolos on the first line of the second page.
2. Khachaturian Concerto - Mvt. 1 - Starting the section at mm. 74 I play most of the C#'s during this passage with the Trill key because of intonation and length of the notes.
Mvt. 3 - Lots of the trills and grace notes in this movement are B-C#.
Those are two pieces that come to mind. Most of the time I play something automatically with the C# trill key. I just don't think about it any more.
Schoolgirl, you might not have a need for the C# trill key just yet. Your C# trill key is the key that, if you turned your flute to look at it from the side...it is the highest key. It's also the key that opens the tone hole next to your thumb key. Use the above links to find out about how and when to use the key!
-Dennis
