You`re bringing up so much music I like (but then I like so much).
The ones you mentioned that I know are:
Grieg- Great piano stuff, including a beautiful Nocturne (if memory serves), etc.
Sibelius- Love his Violin Concerto (do you know it?), just beautiful. I think I actually prefer it to Finlandia, which is great also.
Carl Nielsen- (yet another Dane, as I had recently discovered before you mentioned him. Wondered if someone would bring him up!) Although I haven`t listened to them in a while, he wrote a piece for oboe (sonata?) and a wind quintet which is also great, once again if memory serves. Have you heard the quintet? I must give these a relisten!
Kuhlau- Of course as I teach piano, I`m familiar with a few of his Etudes, Sonatinas etc.-fine works.
Hartmann- The name is familiar...hmmm.
Beethoven- The Egmont- very interesting info., thanks. This work is not my fave Beethoven work, I prefer the symphonies and the piano sonatas, and there`s another overture (I forgot the name!) that I like better too. It`s still a great work though, of course!
Tchaikovsky- the 1812 overture has to be one of the most exciting works! So many of his works are wonderful.
If anyone wants to join in this discussion, feel free! The more the merrier!