Trust me: You don't need to stop a single second more. the other attractions are models (you are traveling with your mate) and expensive shops (the stuff can be brought everywhere else in Europe main cities).

I always bitch why foreign tourists need to stop in Milan, when small cities (VErona for naming one) are already more interesting, and a big one like Turin should be head and shoulder above Milan for any tourist in his right mind.

Airport Logistics, I presume. So if you are not bund to it, don't make the mistake: stop over night in Turin, and look at Milan en passant on the way to Venice or  Florence.
From Geneva, it is a little bit difficult maybe, but from Lyon, Turin makes perfect sense.

La répartie est dans l'escalier. Elle revient de suite.