I know here at Boston Center management is pretty accommodating about giving tours to foreign ATC specialists. We have controllers from Montreal and Moncton Centers come through quite frequently. We also has some French ATC students come through two years ago and they got to monitor operations on the control room floor.
That being said, each facility handles tours differently and we have some incredibly lazy a-hole mangers who couldn't be bothered to extend professional courtesy to colleagues from across the pond. If you don't get any satisfaction dealing with FAA management, another option is to contact the NATCA(union) representative who could probably grease the skids for you. The facrep at MIA is Jim Marinitti(
[email protected]) and at ZMA it's Steve Wallace(
[email protected]).
Best of luck.