My family and I will have a few hours to see Siena as one stop on a day trip from Florence (no, spending the night and/or cutting out our other stops is not an option).
If you could only climb one, would you choose Torre del Mangia or the Facciatone (the view from the unfinished facade at the Duomo museum) and why?
I don't know what the facciatone is unless you are referring to the observation deck at the cathedral. I have done the city hall tower (Torre del mangia).
Here's my two cents - if you are going to visit the cathedral - just go to the cathedral observation deck because it will included in your pass and you will already be there.
The Torre del Mangia gets very crowded midday. You will have to put your stuff in a locker which is included at no extra charge with your admission fee. You can only take up a camera. Your neck wallet, etc. needs to be UNDER your clothes. Nothing dangling is allowed for stair safety reasons. If you are going to do this tower - my advice is get there right when it opens which I believe is 10 am. Start descending downward by 11:30 am. Otherwise, the staircase is an absolute tourist crunch. You will end up pressing your body against a wall to make your way down. We traveled there during June, peak tourist season.
I would hike this tower again, but only if I could get there when it first opens or 2 hours before closing. I don't like being a human sardine in a can.
Torre del Mangia, probably. I didn't get the tourist crunch but it was October and I went in the morning within an hour of opening. The light is better then on the Campo anyway. From here, you get a view of the Campo, the countryside, lots of the city roofs, and you can see the Cathedral (the back of it anyway) and San Domenico. From the Facciatone, you get a nice view of the side of the cathedral, countryside, and the Torre, but not so much campo that I remember. The nice thing about this is that they have a limit on the number of people so no big crowds, but I don't remember if they had reservations since I got there and waited in line until they were ready to take another group up.
The other option (because it's not enough for people to live in a hill town, they also have to build tall things with lots of stairs) is the Opa Si pass for the Duomo and include the Porta del Cielo. It's in the cathedral itself and goes up to a balcony where you get a view across to the Facciatone. You also have a view of the cathedral floor, close up of the dome interior, and a little of the construction since you're "behind the scenes".
But for the best general views, the Torre. Then go get lunch and have a picnic on the Campo with everyone else.
