I've always been weak for the "decorations" in baroque music
Although I don't like Vivaldi that much. Stupid reason, really... I had to OVER-analyze him in Music theory class when I was younger. Kinda ruined him for me.
But J.S.Bach and Händel are awesome.
Of the Classical era, I'd have to, of course, pinpoint Mozart and Beethoven. But I don't enjoy listening to classical as much as baroque.
You mentioned Tschaikovsky: I looove 1812 Overture!! One of the biggest shiver I've had in my life was when I heard it live. It's wondersome.
EDIT: Oooh yeah, Albinoni!! He's great. I like his oboe concertos (or the ones I've heard / played)