Ah I hope I'm not too late on this thread!
Like everyone said, squats are fantastic. Lunges are great too.. both preferably weighted if possible. You can also try plie squats.. and even plie squat jumps. Squat jumps are killer! Something else I was doing for my back was "supermans".. or "supergirls".. here's the form:
It's supposed to help strengthen your back but I was seriously noticing some burning in my glutes as well! What you're supposed to do is lay on the floor, bring yourself up into that position, pull in your belly button, and squeeze your glutes really hard to hold yourself up. Hold the position for 5 seconds and then come down again. That's 1 rep. Do 3 sets of 12 reps. I think this could be used in either a back routine OR a butt routine because it really works both.
This is another workout that I add into my "leg day".. I LOVE it and HATE it at the same time. She calls it a "thigh gapping" workout but.. eh.. I wouldn't really
say that it is exactly. If you're building muscle on your inner thighs, it's not going to really give you a gap??? I don't know.. but it's a really really good workout! Half way through the part where you lie on your side I'm yelling lol. It hurts SO good lol.
She actually has a lot of other great videos too! I also really like her attitude.. she's just really nice and peppy and just seems to really enjoy what she's doing.. even though it's not always enjoyable lol.
Finally.. something that you really have to do is cardio! I run every single day and I've noticed a huge difference in my legs and butt. The "chunk" is fat. You can't get rid of that with strength exercises because that's just building the muscle under it. The fat lays on top. To be able to see the muscle you must minimize the fat! This means, cardio and a proper diet! It will make a huge difference!