I'm having a Silly Symphonies moment right now, especially King Neptune (1932).
So much so, I made you a gif of my favorite part, the sweetest whirlwind of animated mermaids. I wish this was my own personal aquarium.
I got crazy about the Fleischers a few years ago and my Ub Iwerks DVDs have seen lots of use, but I really hadn't spent that much time poking around in the post-1930 Disney vault 'til now. There's so much to see!
I've spent most of my time looking at slightly earlier cartoons, and it's amazing to see the jumps in fanciness a year or two made in those formative days. I guess that's like anything, right? The beginnings of things happen in leaps, not hops.
If you're interested in this kind of thing, I highly recommend Of Mice and Magic, Leonard Maltin's book about American animation. My friend Devlin (who has pointed me in the direction of lots of excellent old cartoon tomfoolery) recommended it, and I wolfed it down. It's a fascinating book - I especially loved the long bit about the trials & triumphs of Walt Disney, about his working philosophies, etc.
There were a handful of brilliant men obsessed with craft and cleverness in the 20's & 30's, when animation was still quite young. Moving treasures that sprang from hundreds or thousands of drawings - I just feel lucky that so many have been preserved and/or restored and are so easy to conjure up any old time.