Well for your consideration, we excitingly present these wonderful options. On a side note, a favorite with ease is Fiesole (hint, hint).
Siena
Siena is a beautiful Tuscan hill-town with an illustrious past. Famous for the twice-yearly
Paliocontest, when horses race around the sloping Campo, Siena also has plenty to
offer tourists at other times of the year: art; churches; museums; narrow picturesque
lanes; views. SITA run express buses from Florence to Siena, departing from the SITA
bus station (approximately hourly). The journey takes an hour and fifteen minutes. Trains
are not such a good option: the journey takes nearly two hours (although a new railway
initiative, the ES link, provides alternative coach travel to Siena). If you take
the train you will need to catch a local bus from the railway station into the heart of Siena.
> More information about Siena
Medici Villas
The colourful Medici family ruled Florence for many years (on and off). They appreciated
life's comforts, and had a number of fine villas built for themselves in and around
Florence, complete with splendid gardens. Several, including the lovely Renaissance
villa at Poggio a Caiano, can be visited by the public, and make a pleasant
excursions for tourists with an interest in history or architecture. The Florence
Tourist Information office supplies an English-language leaflet with descriptions and
useful information for getting to the villas.
Fiesole
Fiesole was once more important than Florence. Long since conquered and dominated
by the newer city on the plain, Fiesole has subsided into a peaceful, attractive place
with famous views over Florence. The small town is a good destination for escaping
the heat and crowds of the city - you'll see from the grand villas how many of
Florence's wealthier residents have escaped here in the past. Fiesole is a short
trip from Florence on an urban ATAF bus. Bring a snack to eat in a panoramic
little park. You don't need more than half a day to see Fiesole, but your outing can
be extended by walking around the lanes - or even back into Florence.
> More information about Fiesole 
San Gimignano
San Gimignano is famous for its medieval skyscrapers - fortified towers which were
built by the hill-town's competing families. Today San Gimignano is a tourist honey-pot,
but is still charming enough to win over the sceptical visitor. To get to San Gimignano
from Florence, take a SITA bus or train to Poggibonsi, then change to another bus for the
short journey onwards to San Gimignano.
> More information about San Gimignano 
(I liked how this guy did the kick instead of the push)
Pisa
Pisa and its famous Leaning Tower are just a train trip away from Florence. Few
tourists in Tuscany will want to return home without a photograph of one of
Italy's most celebrated landmarks, and there are plenty of other sights to interest the
daytripper. Trains run to Pisa from Florence's Santa Maria Novella station, and
travel time is just over an hour.
> More information about Pisa Tuscan countryside
There is some beautiful countryside very close to Florence: rolling green slopes
capped by fortified villas; vineyards and crumbling villages. If you have a car, you
could spend a day just exploring Tuscany, stopping off to visit vineyards and
other sights. It's more tricky to roam using public transport, but not impossible: for
example, we took the slow bus to Poggibonsi and were very impressed by the
countryside and villages we passed through. An intrepid traveller (ideally armed
with a bus pass) would enjoy taking in the view from bus windows, and hopping
off on a whim at interesting locations.
More suggestions
Arezzo is a dignified historic town on a hill topped by a large park and ruined
fortress, easily reachable by train (a range of types; the fastest is Intercity which
with superb views over Tuscany and Umbria, and is an hour and twenty minutes
by train from Florence (followed by a local bus from the station up to the town).
Lucca, the walled town so popular with overseas visitors, is approximately an hour
and twenty minutes away by train.
to see Italy's capital, then be bold and take the fast Eurostar train service for a busy
day's sightseeing. Be warned, though, you will only be able to get a frustrating
glimpse of this fascinating city's charms.
