Hey CW! Welcome to DBB.com!
Pure's right on with the back squat advice. To that, I would add deadlifts and lunges. Deadlifts are so effective at putting meat on my butt, that I have to cycle on and off them every couple of months -I'm literally outgrowing my trousers, and it's getting expensive
For glutes and hamstrings, deadlifts and Roman Chair back extensions can't be beat. lying hamstring curls are okay for getting a nice pump and a mean burn going, but I find they don't hit the hamstrings nearly as hard as deads, and they wreak havoc with the back of my knees. Same thing with leg extensions -great for building the vastus muscles ("teardrops") near the knee joint, as well as the quads along the front of the thigh; but if you want to widen out your upper thighs,
NOTHING beats squats
Unless you already know where you tend to store extra calories, I wouldn't recommend the "eat more and see where it lands" approach. localized fat storage is largely determined by genetics; and just like there's no such thing as spot-reduction, there's no way to selectively pad up one specific area with extra body fat (discounting injections

).