Hello all!
I was wondering if anyone could help me... I seem to have a lot of trouble moving my ribs and hips without moving my shoulders (the way latin dances are supposed to be danced.) I'm not exceptionally flexible, but I don't think that is it. Thank you for your input!

It's not so much that your shoulders don't move, it's that they move less than your ribs and hips. The main thing is that they don't go up and down..it's impossible to move your ribcage without moving your shoulders at all! For practice, try sitting in a chair and stretching only your upper body...to the left side, left ribcage forward, right ribcage forward, to the right side, back...then back the other way. Then, try holding a wall or dresser to hold your upper body still while you do weight changes or something to work on the lower body. Then try all these motions without anything restraining you, so you learn to do it by muscle power. Think about stretching your ribcage in the opposite direction from your hips. Good luck!

Dancing requires muscle groups to be used in isolation in a way which is generally unnecessary in normal life. It's not that you're lacking flexibility - this is not likely to be a problem - it's the brain and neuro-transmitter system that needs to be educated so you control the muscles correctly.
A previous reply has made sensible suggestions - basically you must learn to move in a certain way.
My advice - learn one thing at a time, and start SLOOOOWWWLY so you have time to think about what's happening. work at it every day on your own in front of a mirror if you can.
i used to have a lot of trouble with my right shoulder in ballroom (it would raise up at certain points). I practiced dancing around at home in front of a mirror holding a weight (actually a loudspeaker!!) against me with my right arm. It worked! I got used to doing the moves with my shoulder DOWN.
The learning centre used to have something on hip movements - it had good practice routines.
So - work on the movements that give you problems and they will improve.