I've also been dangerously addicted to the 1st movement of the 3rd. I've forcibly put it on the shelf until the score arrives. But thanks to that I've gotten to know that mvmt really well. It's still my favorite mvmt of that symphony, but the final mvmt is close behind.
Maybe it's just me, but I just hear Shostakovich 5th everytime in that opening. (The rising horns with the full orchestra dum-dum) The 3rd and 5th have openings that just grab you by the throat. I'd give anything to hear those symphonies live!!
So many great things just in that 1st mvmt. of the 3rd. The contrast between the funeral march of the frozen earth and the sweet and boisterous sounds of awakening summer. The light and the dark side. (I like the
dark side better!

) I love those falling trombone glissandos, especially when they're really nasty! His brass writing is to die for.
There's this one moment that I adore the most: It's after the first long trombone solo, when the whole section comes in, and suddenly goes into this fanfare in a major key that slows down and ends nastily back in the minor key with the full orchestra and a muted trumpet call. (In Chailly 9:14-9:25, and he's got some low-down dirty trombones!)
Then this nationalistic march out of nowhere, which sounds English to my ears. Crazy. And Chailly plays it so cute and mockingly.

Such proper stiff-upper lip playing when a few minutes before they were unwashed brutes, I love it.
At around 17 min is that the posthorn solo? It sounds a lot like a euphonium or baritone. I think they're close to the same thing.
Then the circus appears! (With the shrill trilling winds and tamborine and oom-pah accompaniment.) But it's kind of like a broken amusement ride. Especially with the off-kilter snare drum cadence, this part right here is so Ives to me!
And suddenly we're back at the beginning again. Winter tries one more time but her trombone is seized by the haze of summer and ends up swooning in the major key. Leading tones are used to great effect in his themes here.
For the last time, summer marches in from the distance, with great pompous fanfare. And what's this, the trombones have submitted! They take over the melody, joyfully, happily singing a song of summer.
And finally everybody dances around the Maypole, rounding up with a perfectly royal brass chorale and fanfare. (God, the brass players must have their lips falling off by this point.) The ending (the last minute) is so brilliant, another favorite part.
Charge!!And, I wasn't going to listen to the while darn mvmt again! Dang it, Sarge...

The 7th is best taken a movement at a time, and I do find myself listening to that mvmt often. But like the 3rd, it's also locked away until I get the score! Again, this macabre march weaving in and out of major and minor, like a broken music box. Utterly hypnotic. There's so much I still don't understand about that symphony. Which is why I love it.
*This post has been edited because I had too many emoticons the 1st time around. See what Mahler does to me?!
Ach, help!