We use Special Kitty brand litter from Wal-Mart it's a good clumping litter for the price and with 6 cats and 7-8 litter boxes we go through a lot of litter. I also love the Clump & Seal from Arm & Hammer, it's a very tight clumping litter but it's expensive so I'll usually pick it up on sale and mix it in with the other litter to extend the life of the litter.
We use plastic tubs and hooded boxes mostly. I had to stop using the open boxes because we have one "elevator butt" who stands up while urinating and pees on the walls
and one cat that pees as soon as all 4 feet are in litter so he tends to go over the side of standard boxes.
Right now we've got 3 tubs, 3 hooded boxes and an extremely large open box (biggest one I could find). I've got another tub I need to set up this week.