I been keeping some lists, and since the characters have not changed for several months here are the locations, but be warned they will eventually move and then you should search around for them,
monty
Mac - in living room at his appartment
Terrence - in his room last door on top in Macs appartment
Goo - in Lobby
Mr H, Fourth floor records room (bottom row 2nd door from the stiars)
Bloo office on fith floor (accross from box office)
Madam foster in Theater fifth floor
Frankie in dressing room in back of theater fifth floor
coco in tlescope room 6th floor
Ed in locker room six floor
Wilt in Gym on six floor
Dutchess steam room six floor