If both tours depart from Florence, the one going to Impruneta would be a short one, technically not even as far as the Chianti Area. Impruneta is the municipality immediately to the south of Florence city limits.
The one going to Siena and Monteriggioni (assuming the starting point is Florence), is a major Vespa tour that will take the whole day, and you will feel it in your derrière at the end of the day, if you are not used to long motorcycle rides.
I am assuming you are an expert motorcycle rider at home, because if you are not you shouldn’t take either tour. Riding motorcycles or scooters is inherently dangerous anywhere, even more so in the twisting and narrow Tuscan highways. An inexperienced person who has never been on motorcycles or motoscooters shouldn’t try it in Italy the first time.