I've never been to Gleasons and am very envious. Please post trip report after your first workout.
There are already a couple of threads on this subject here (try the search function, n00b [img]/images/graemlins/smile.gif[/img]), but if someone starts trying to have you spar right off the bat, they're likely more interested in you as gym fodder than they are in teaching you anything.
Edit:
Try this thread.