10 days in Italy

My main recommendation would be to take one of the discount European flights, rather than a couple of long train rides; you're covering lots of distance. The plane also will probably be cheaper. Check skyscanner, and the individual airline websites. Only you can decide about Florence. I can't imagine skipping Florence for extra days driving around Tuscany, but your interests may differ from mine. My first visit to Florence was 10 days, and I could have spent more time there. You message talks about 8 days, not 10. If that's the case, I'd pick two areas, not three, but again, only you can decide whether you prefer depth or lots of variety.

Sounds like a great itinerary. Two weeks ago we just returned from a 12 day, our second trip. Both times have skipped Florence since neither one of us is that huge on museums and conjestion. There is a heck of a lot of great art throughout Italy not in museums. Would only go to Florence for the "Greatest Hits" On this last trip we went to Sienna but ended up not even parking it was sooo crowded! We stayed in a B&B just out of San Gimingnano (Il Casolare di Libbiano) and it was wonderful! Only downside it could make you want to spend all your time there soaking in the peace and quiet! Note: Last year Sienna in March was a whole different story-no crowds at all.

Sounds like a great trip plan, so far!! Does this imply 10 NIGHTS in Italy? If so, my preferences would for sure add on two nights in Florence! You say you love architecture, and this is the location of the birth of the Renaissance! So, if time's there, go for it! Brunelleschi's dome is so much more of a site in person that I'd imagined, and to see things like the "David" and Michelangelo's unfinished works at Academia -well, it's nothing short of inspiring! Not to mention ALL of the palaces, and outdoor architecture you'll see just walking around this compact historical district. (Tip! With limited time, either SPLURGE on Firenze Card to skip the lines at sites, or COMMIT TO A TIME and make a reservation for your top couple sites! Limited time can't afford a 3 hour line when you're flying all the way to Italy!
As for the countryside! Loved it!! Don't drive in Florence! But, head south on the Chinatigiana highway, I'm sure someone can add more info on route/ road# It's beautiful! It connects florence to Siena - meandering through vineyards, olive groves, and amazing Chianti-region towns like Greve or Castellina. You stop for espresso, wine, lunch, go by vineyards (call in advance!). It's lovely!

(Part 2- I talk too much) ... After Florence, We spent 3 nights in Siena, and 2 in Orvieto (in Umbria). Orvieto was lovely, and you can spend a day walking, doing the nderground tours, drinking the Fantastically underrated Orvieto Classico white wines, they're great! It's the type of place where the people are so charming you get to know your chef/owner at your restaurant after dinner as they make their way around to ensure everyone is having a great meal. They tell you their preparations, where the vegetables and pasta comes from, they chat about life and wine, and they welcome you! From Orvieto, a FAVORITE day trip was civita di bagnoregio in the morning. Civita looks like a mystical little medeval wonderland, just google image it, youll be enamored. Another great day trip from north or south is Montepulciano. It was spectacular! I loved it there! Oh, the food, the wine, the scenery. The tasting rooms! Fabulous! Up and down narrow hills lined with cafes and shops, and wine rooms, all surrounded on the outskirts of town, by a breathtaking view of the valleys and plains ping off below the village, spanning out to the Tuscan countryside every which way. Siena was fantastic, lots of hilly walks, shops, gelato, views, great sites, great food. Il Campo is fun to just hang and people watch with a gelato. You can easily travel into Tuscany or Umbria from there, but for sure spend a day in the town your staying in. Get to know your neighborhood. Most important, pick a few places, and settle in, AT LEAsT 2 nights (hopefully 3-4) at a time. Tuscany is slow good, so it should be slow travel, in my opinion.
Have a wonderful special trip, you will go back. So don't try to fit too much, or you miss the magic of the moment you're in.

Thanks a lot for the input guys. We are still working on the iternary..will share once finalised. Cat...special thanks for such a detailed post.

If you enjoy Architecture- FLorence is INCrEDIBLE !! We just returned from Italy and stayed 2 nights in Florence right in the Historic District-it is very compact and very walkable- of course depending on when you are going to be there it also can get VERY crowded.
I would recommend tickets for any sites you MUST see such as David etc.. but we enjoyed walking and viewing all there is to see OUTSIDE... Pictures in fact do not do it justice !! Have a wonderful trip- have some good recommends for FOOD in FLORENCE as well- we REALLY enjoyed the EATS in FLORENCE !!