It sounds like you might benefit from some weight training. From what I've read, one of the only ways to help reduce cellulite is to firm up the muscle underneath, and toning will also help the "saggy buns". My favorite upper-leg weights are hip abductors and adductors; I know a lot of people also use squats and leg-lifts to keep their legs toned. (A quick internet search will tell you how to do all of those things, if you don't already know).
As for diet (which is a really controversial topic around here!
) I personally would recommend a simple low-fat, balanced diet with plenty of fruits and veggies. No diet is going to get rid of your cellulite, because even the tiniest amount of fat poking through those connecting fibers in your legs is going to cause cellulite, and it would be impossible (and unhealthy!) to eliminate all the fat from your legs. If you already eat mostly right, I wouldn't change your diet.
Good luck!
help: PONES! 
