Need help with itinerary for first timer in Rome and Tuscany in cold February!!!

Book a Wine Tasting and tour at Biondi Santi if you drive down to Montalcino area for the Brunello's. I loved that one, also San Polino is nice winery too. If you like wine you can spend 1 whole day south of Siena around Montalcino and Montepulciano.

Florence alone can fill up 2-3 days depending on what you like. Rick has a good list in the At a Glance section depending on what you like. https://www.ricksteves.com/europe/italy/florence You can spend half a day alone in the art gallery of the uffizzi.

You can probably skip the CT all together. Not much will be open and most people leave the area over the winter.

Always the first recommendation -- hit your public library and pull tour books and travel DVDs related to that area. That should give you your list of common must sees and do's. From there return here with specific questions about your schedule. At the moment it looks a little too busy. With three days I would drop CT since it is some distance from Florence and Siena. That area can easily occupy three days, in fact, it could occupy a week. Under like CA, the Italian wineries generally require an advance reservation and a fee. A couple of years ago Wine Spectator had a list of great Italian winery to visit. We used it to great success.

If you only have "3 days to explore possibly Siena, Florence, Cinque Terre" I would say, stick with Florence. The city has so much to see and is so beautiful. If I understand correctly, you will be staying in Pisa and you will have a car. If that's the case, you can make some stops en route to & from Florence to enjoy a couple of the smaller villages/towns.

Get a guide book on Italy; you have enough time; to reiterate you can get current editions of these at Oakland or San Francisco public libraries or just buy it online; they even come in e-book format so to lighten your load on a tablet or phone they generally outline the so called "must sees" and "must do's" and you will be able to read, research, organize, and better decide for yourself what is worth your time and money in Italy.

and it is not cold there in February; no snow or ice

Hilton Vacation Club in Pisa

Lark, are you staying at Hilton Grand Vacations Club at Borgo alle Vigne? I was curious where your vacation club was located and this was the closest listing I could find for "Pisa".....except that it's not "in" Pisa at all. According to some reviews, it's a 45-minute drive or more from the Pisa airport depending on traffic. That's not necessarily an issue if you're aware of that but your use of "in" raised the question.

With only 3 nights (is that correct?) at the resort, you'll realistically have 2.5 days to explore from that base so you'll need to be selective. Florence will easily eat one those days so that leaves you just one more full day for a winery and sightseeing. In February, I would probably skip the Cinque Terre in favor of Lucca or Siena, and do read up on the ins-and-outs of driving in Italy (ZTLs, International Driving Permits and whatnot) if you haven't done so? For instance, you'll probably want to leave the car on the outskirts of Florence somewhere and take public transit in but trusty RS poster Roberto (and others) will likely weigh in with good advice on that issue.

Are you returning to Rome on your last day prior to flying home?

Congrats on your upcoming 50th; Italy will be a great place to celebrate!

The Hilton Vacation Club is actually in the rural Val d'Era (Era Valley) between Pontedera and Volterra.
You could also consider renting the car in Florence, instead of Pisa. You can reach Florence in 90 min by fast train (vs 3 hours to Pisa). If you rent from Hertz, choose the Hertz location on Via del Sansovino, which is on the way to the freeway to Firenze-Pisa/Livorno. Exit at Pontedera and go toward Volterra. If it were another time of the year, I'd recommend to rent the car in Rome and drive, but in February maybe it's best to minimize driving. The driving from Florence is not much longer than from Pisa airport.

The weather in February could potentially be 'freddo' (cold) and possibly 'piovoso' (rainy). Snow is unlikely at low altitudes. Temperatures in Tuscany are similar to Northern California, so not too different from what you are used to.

Given the season, you may want to skip the Cinque Terre.
The Hilton is very close to Lajatico, Andrea Bocelli's home town where he has a ranch and maybe he'll let you ride one of his horses, since I'm sure he had enough of his horses after last month's horse riding accident. But there isn't much to see in Lajatico, so I'd forget about Andrea Bocelli, and drive a little further up to Volterra, which should be a must given your proximity.
Siena or, the even closer Lucca, would be great choices to visit. To visit Florence you might even consider driving to Pontedera and taking the train from there. If you go for the day you'll avoid the commute traffic into and out of Florence. If you drive all the way in, consider parking at Villa Costanza parking lot then take the tramway streetcar line T1 from the Villa Costanza Parking to the central Florence Santa Maria Novella station.