Left bin (directly under my table):
>top drawer: vehicles and other assembled objects that I want to save for later use
>middle drawer: Round Pieces (curved plates, 2x2+ cylinders and cones, curved slope bricks, etc.), Storage Containers (boxes, cabinets, treasure chests, trash cans, etc.), Space Windscreens, Small Windscreens, Modified Plates (clips, with handle, etc.), Hinges, Rocks (BURPs, LURPs, TURPs, and dark gray/bley plates and bricks), Car Parts (seats, steering wheels, air scoops, grilles, mudguards, chassis pieces, motorcycles, etc.), 1x1 and 1x2 SNOT Bricks (1x1 and 1x2 SNOT bricks, Travis bricks, headlight bricks, etc.), Larger SNOT Pieces (larger SNOT pieces), and Panels
>bottom drawer: Technic Pieces (pretty much everything but rods and bushings), Castle Walls, Wheels and Spinny Things (wheels, 2x2 turntables, etc.), Technic Panels, Castle Parts (arches, parapets, dungeon doors, etc.), Stairs (straight and curved staircases), Space Parts (rockets, dishes, other typical Classic Space pieces), Supports (beams, etc.)

Middle bin:
>top drawer: Plain Heads (plain smiley minifig heads), Non-Plain Heads (all other minifig heads, including blank heads), Headgear, Neckwear, Hair, and separate bags of components for each of the ongoing games
>second drawer (this bin has four drawers): unsorted bin mostly full of minifigs and pieces that I just threw in because I needed my table cleaned off for the next game and I was lazy about putting things back where they belong
>third drawer: Plants (separated into bushes, leaves, etc.), Trees (2x2 cone and round trees), Beasts (separated into Sea Life, Birds, Small Mammals, Rats, Creepy-Crawlies (snakes, bugs, spiders), Windows (separated by type of building windows), Doors (separated by type), Boats (boat hulls, pirate ship hull sections, lifeboats, rigging, masts, etc.)
>bottom drawer: Baseplates

Right bin:
>top drawer: Long Things (antenna, Technic axles, bushings, Technic pins, hoses), Printed Pieces (basically every printed piece, 2x2 computer slopes, 1x2 $100 bills, except flags), Coverings (1x2 grates, fence pieces, tiles, modified tiles, cheese slopes, jumper plates), Minifig Stuff (weapons, utensils, skateboards/surfboards, Footwear, Luggage, Medical, Home Health & Beauty, etc. broken down into smaller subcategories like Swords, Shields, Skis, etc., Flags (all cloth and plastic flags), Minifig Torsos (separated by torso color, also a bag of loose arms, a bag of loose arms with printing, a bag of loose hands, and a bag of the modified Basketball arms, Minifig Legs (separated into plain, printed, short, and dress slope/modified (includes peg legs, faun legs, ghost legs, etc.)
>middle drawer: Plates (each type of plate from 1x1 to 2x10 has its own bag, 4x6s have a bag, angled pieces have a bag and are divided by type, and all larger pieces are in another bag
>bottom drawer: Bricks (separated by color), 1x1 Bricks (1x1 bricks of all colors)