Florence is a very popular place for guided tours and a traveler will have no problem at all finding one to suit her needs. Browse tours and purchase tickets before arriving, or even just set out to the historical center of town and a person can join one there. Sometimes it is cheaper to buy tickets online beforehand, so it is always a good idea to at least check it out. Art Viva (link in References section) has been in the game for a long time and has a great reputation.
Even though having a guide to show you around and share their insider knowledge of the city is nice, it generally does not come cheap. But that is OK for more budget-minded travelers, because many resources are available for setting out on your own self-guided tour that can still be very educational. Most travel guide books and online travel websites have maps that show the best routes and make it very easy to get around on your own. National Geographic Traveler (link below) has put together a few paths that hit all of the Florentine favorites.
With so much to see in a city full of famous landmarks, tours often are geared towards certain interests, such as art, churches, architecture, shopping, history, local wines, dining and more, to keep the influx of new info more focused. Other ones aim to give a broad overview of the main sights and cover a mixture of topics, so there really is something for everybody. Avventure Bellissime hosts a combination tour that highlights the best of Florence in conjunction with a trip to Chianti wine country. Find out more about its offerings under the Resources tab.
Traveling with kids can be challenging, especially in a foreign country. But when there are plenty of family-oriented activities at your vacation destination, it makes it a bit easier, and certainly more fun. In a place like Florence, younger children may not enjoy hours upon hours of walking around and looking at art, but luckily there are options for families that work to keep youngsters engaged. Context Travel (link below, in the References section) is one company that has kid-friendly tours that are sure to entertain the whole family.
One kind of very unique, yet slightly spooky tour that can be found in Florence is the intriguing ghost tour. These are a bit different than any other kind of tour in the fact that they are conducted at night and are more about storytelling than the simple relay of facts. The cool part is that the stories are all intertwined with historical events and real people, so a participant actually does learn along the way, as well as getting a little scared perhaps. Avventure Bellissime runs several ghost tours.
Walking tours range in length greatly, so if a person has all day and wants to soak up as much information about Florence as possible, he can do it at his own pace. If time is more constrained for others and they would rather split up their day between different activities, shorter itineraries are also offered that last a couple of hours, a half day and everything in between. Shorter journeys have the benefit of being easier on the wallet.