The hardest part about going to Florence's museums is choosing which ones are worth your time. With so many different options, you could spend your entire Florentine experience walking the halls of the many museums here. Art lovers will be in heaven--the city is one of the best to see works by the great masters: da Vinci, Michelangelo, and many others are available to view.
It would be an absolute shame to miss the Uffizi Gallery. It's home to some of the most famous works of art in Italy, and you should think about taking an entire afternoon to visit. It's constantly crowded in the summer, and the lines can stretch out long--booking online can help you solve the problem of spending most of your time waiting.
Also make sure to stop by the Museo Galileo if you love science and history. Not only do you get a feel of what life must have been like at that time, but it's also a great spot for the kids to learn about the advancements Galileo made with his discoveries. Another great museum to take the kids to is the Palazzo Strozzi, where there are no exhibits all the time to keep them and you engaged.