3 Months in Florence

First, unless you have a proper visa, make sure it is 90 days and not three months. Three months will get you in trouble. In fact, I would only plan about 85 days just to give a small margin should anything be delayed.

My cousin has lived on Borgo S.Jacopo for years. It's a nice area. If your apt faces the Arno you will have a nice view too (and it will be cooler). There are traffic restrictions there. If you have a car the only way is to park it at an underground parking garage more or less half way on that street. They can put your car in the White List of the City, so that you can access the area. It's not cheap however.
There are a lot of luxury shops in the area. Borgo San Jacopo in particular has a bunch of antique stores. The Oltrarno area was traditionally the less crowded area of the historical center, but nowadays many have discovered it, so there are lots of tourists as well. However you are going during a slightly less crowded period. I don't know what information you need.

Roberto,
Thanks for your reply..........my husband and I love to take the trains in Italy...........in our early years of Italian travel we loved to drive but now we are intrepid train travelers...........we are dealing with a site for the 3 month rental and of course, being New Yorkers, are a little concerned about plunking down a large sum of money to secure the rental..........however, we have found an apartment that looks really nice..........and it's right on Borgo San Jacopo............we can't remember if there is a market close by..........the Mercato is about a 10 minute walk I think but don't know of any smaller markets in the neighborhood...........

The historical center is about 4 square km (1.5 Sq.mi.) therefore nothing is too far.
If you like markets, permanent markets are the Mercato Centrale di San Lorenzo, the Mercato di Sant'Ambrogio, Mercato Nuovo Del Porcellino, Mercato delle pulci of Piazza Ciompi. The first two have plenty of food items, the latter two are more antiques and souvenirs.
Near Borgo San Jacopo, on Piazza Santo Spirito there is the Fierucola (little fair) every 3rd Sunday of the month. It's a market of local organic foodstuff. Every 2nd Sunday of the month on the same piazza they have the Mostra di Arti e Mestieri (antiques and crafts).
You won't find big box supermarkets, Walmart style, within the historical center, as the City doesn't allow those within the ancient walls. However there are plenty of smaller food shops all around. They are a bit more expensive than big box supermarkets, but if you want something close, there is no other choice. If once in a while you want to shop at a bigger supermarket, the closest is probably the Esselunga Supermarket on via Pisana.

As Frank mentioned above, unless you are both EU citizens, please be aware of the 90 day restriction to non EU citizens visiting the EU Schengen area. If you intend to stay 91 days or more, you need to apply for a long term visa. Inquire with the Italian Consulate in NYC. There are plenty of posts here on how the 90 days over a rolling 180 period is calculated. Use the search function.

The first apartment that we wanted doesn't have any air conditioning..........we were in Firenze in July and remember it being hot, but not buggy....................also, no English speaking TV stations.............I don't think I can live with the news............and certainly my husband can't...........

Roberto, I am German born to German parents and a Naturalized citizen so I am going to try and see if I can get dual citizenship...........working on that.............this way we wouldn't have to leave after 90 days if we chose to stay...........

Ciao

Roberto, I am German born to German parents and a Naturalized citizen
so I am going to try and see if I can get dual
citizenship...........working on that.............this way we wouldn't
have to leave after 90 days if we chose to stay...........

On that both of you need to be EU citizens, not just one of you...