Have you tried front squats? They tend to keep you a bit more upright but can be tough on the lower back if you can't handle the weight properly.
Smith squats or smith hack squats always will help you out a bit.
If you don't want to do either of those you can do box step-ups (bb or db) or lunges (bb or db) for your legs.
I always advocate at least 1 standing leg pushing movement (pushing off of the ground i.e. squat/lunge/step-up as opposed to leg curl/deadlift) in any lower body day because of the athletic implications as well as for the obvious benefits of training legs from a natural standing postion.
Leg presses are great for isolation and mass and you can really move some weight, I would def. put them in there somewhere.