There are many choices out there and what I did was attend the Cue-Tech Pool school. I caught up with a class when they came locally to my home on one of their road classes. It was by far the best thing for my game and the best part is that I can retake the same class to brush up on my game for no additional charge.
During my session, there were 5 instructors available to the 10 students. Each taking turns watching and evaluating as you worked on a exercise session.
The best part is the daily evaluation of your stroke on video which you get to see. They take everything apart and show you what is correct or incorrect with stance, grip, bridge distance, stroke, etc.
So you get to see the progress or lack of progress.
Now there are many other schools out there and I am sure you can find one close enough to home to give it a try but look at the following links to Cue-Tech:
http://www.poolschool.com/
http://www.poolschool.info/
Enjoy the game!