ive started to split them up also, my back just could not take both squats and straight leg deadlifts. I like using DBs, and putting the tips of my toes on two side by side 25s. It deactivates the calf muscle in the exercise.

Standing leg curls. I do these after stiff legs and the burn is retarted.

it burns but for me leg curls feel good they don't really make me grow as much as other exercises.

It is nice do do quads squats heavy legs on one day, as takes a hell of of a lot of energy, and concentrate one day on each.

Hams really need more attention and energy than most think ans lots have underdeveloped ones compared to quads.

I take it kind of as a different muscle group, like bi's and tri's...

Stiff leg deads here. I do them on my back day. I also throw in leg curls after I do quads just for shits and giggles.

Yeah, I rely on the deads for mass b/c you can use so much more weight, but when you isolate one at a time and go real slow down and explode very quickly to the top, you can't beat them.