Library is out of the question. Supposed to be quiet places.
Sports Centre - can't think where, the only places in there with ceilings possibly high enough are used as sports halls, the foyer isn't big enough or high enough.
Same with the college, only places maybe high enough and big enough there would be the gym or main hall. These are regularly used for exams so thats not an option. In any case the college isn't a place where the public in general go on a regular basis unless they are studying.
Can't help thinking it shouldn't be in any retail establishment that isn't owned by the council, otherwise the same thing could be happening again in a few years time.
Quite like Bob's idea of it being integrated into the Bus/Rail development some how if undercover space is available.