I'm a bit late to the forum but I thought I would put in my $0.02.
Firstly I better warn you - it can be a slippery slope - I started off listening to a bit of classical (much like you, starting with lively big orchestral pieces with plenty of percussion) and have moved through several stages of addiction to now where I am craving historically informed performances of baroque music - Trevor Pinnock is my new hero!
For big, lively and maybe a even a bit angry music, I would point you to the Russian composers. Tchaikovsky's 1812 overture as mentioned is a great start, especially if you get a version with real cannons and great dynamic range (these CDs come with warnings on them about speaker damage). Beethoven's 'odd' symphonies (5,7,9) are also worth a listen. However, the thing that got me in was the shorter pieces of music such as nocturnes, polonaises and concertos. I find that whole symphonies are pretty hard to get familiar with and shorter pieces make this easier. Think of long pieces like symphonies as obscure concept albums from early day prog rock bands - only people dedicated to the band who are able to piece together the songs in the album to form a story after listening to it many many times are going to truly appreciate them (as a Pink Floyd afficionado, that's how I came to view classical music). It's much easier to be familiar with a single song rather than a complex obscure album.
If you want to start decoupling the instruments and appreciating the musicality of separate instruments (which was my mistake) then something like Chopin's Nocturnes (especially Opus 9 number 2) and concertos from a range of composers (a couple of my favourites are Mozarts concerto for flute and harp and Bach's harpsichord concertos). I like concertos because they are relatively short (usually 10-20 minutes) and even this is divided into 3 parts, with the first part usually quite lively, so I find it quite easy to get to know and like a concerto by firstly listening to the first part - if you don't like it after a couple of listens, you can move on. If you want to do the same thing with more instruments, look for the concerto grossos (which feature more than one instrument as the feature instrument).
I've rabbited on a bit and my advice probably makes it clear to those classically trained that I'm a newbie in this field with pretty sparse knowledge but I thought these few points might help.