Originally Posted by Perche

That leaves you some choices, I think you're going to have to pretty much eliminate a city.

You could land in Bologna and head into the city. I don't know what your luggage situation is. I'd only have a carry on. Store your luggage at the Bologna train station, do some sightseeing, and have lunch. You generally don't need reservations for lunch. Around 5 or 6, take the half hour train ride to Florence and check into a hotel. Walk around to see some sites, then have dinner in Florence (you'll need a reservation).

The next morning could be be tough. It's an hour train ride to Pisa, so you'll need to leave the hotel around 8 AM, which isn't easy after a late dinner. After the meeting in Pisa you can spend an hour or so looking around, then head back to Florence for more sight-seeing and lunch, but you'll probably want to sleep and have dinner in Arezzo. It's an hour away by train from Florence, sometimes longer depending on the train, so you don't want to make that trip early in the morning. It's too much to get up early in Florence and take 1+ hour train rides for 9AM meetings two days in a row.

After the meeting in Arezzo take the train back up to Florence, store your bag at the station, and explore Florence again, this time having lunch there. But you probably want to sleep in Bologna and fly out of there, so leave Florence in time for dinner in Bologna.

Some could argue to spend the last night in Florence and take the train to the Bologna airport for your 12:30 flight, but that's too stressful. You'd want to be at the airport around 10:30, and it's a 1.5 hour train ride. Any glitches with the train, and you miss your flight. Sleep in Bologna, and get to the airport relaxed.

This gives you 2 afternoons and an evening exploring Florence, lunch, dinner, and a hotel night in Florence. 1 day, and an evening exploring Bologna, lunch, dinner, and a hotel night in Bologna. Short shrift to Pisa and Arrezzo.

There are different variations you can do, but I'd play it something like that.