otoh...
i love the falls. the airport is on the west side of toronto. it takes the niagara air bus about 90 minutes to go from YYZ to niagara falls. i would book both ways on it, book a bed and breakfast in either Niagara on the Lake (perhaps my favourite small town in the whole world), or niagara falls. i'd see the falls, maybe see a shaw play in NOTL, eat fabulous food in NOTL at one of the wineries, and consider myself fortunate.
OR
if you like big cities, TO is a nice one. you could see a musical, eat fabulous food downtown, visit the ROM or the AGO....
either way, it will be great : )