Especially because our Florence hotel was unfashionably near SMN
station, we found the bus to Fiesole (one day-trip) convenient. But
I'd echo the NY Trip Advisor advice, "To see [Florence], stay in
[Florence.]" Even if you've been there before, who wants to be trapped
in a pleasant but small city? I grew up in a big city, so I'm used to
waiting times and delays with mass transit. But people who only use an
SUV can get impatient. BTW, I need air conditioning in this area in
summer. YMMV.
It also seems illusory to view Florence (Fiesole?) as a Tuscan town. Yes, it's
elevated, and it's in Tuscany. But it's not like San G or Siena or
Cortona. It has a nice Roman amphitheater and a few things to see, but
I just don't see how it's an improvement on Florence.
I'm trying to see if there is a compromise, but bottom line is that a 25 min bus ride back to your villa/apartment/condo in Fiesole because you're in central Florence & forgot something or just want to take a nap and let the others go do their thing...that extra step can be a drag. The preconceived idea of a 'Tuscan villa' is beautiful, but for at 2-3 or our group that have never been to Florence, yeah, Tim. Stay in Florence.
We've stayed at Piazza Santa Maria Novella, pretty much across the street from the SMN station, and I really didn't think it was too unsavory. So convenient to almost everything. In fact, there was a Nigerian panhandler guy that 'patrolled' the piazza & tried to sell me an amulet the first day, I said no. But I met him the next day doing his rounds, and we struck up a conversation. Nice, intelligent guy, spoke English well, ended up giving him a few Euro, and we acknowledged each other each day from there. Not a bad thing.