Prior posts indicate you've traveled in Europe before. What is important to your wife? Is it seeing specific sites or having a cultural experience?
Even with 10 days, I'd avoid the temptation of trying to do too much. I'm thinking you could spend some time in Florence, then spend some time in an agriturismo in the Tuscan countryside, using the agriturismo as a hub and exploring Tuscany in a car.
If you go to Florence, especially that time of year, I suggest using Walks of Italy. Through them you will get a guide and skip the line tickets. If you look into staying at an agriturismo, which we have done, check their amenities. Some may not have air conditioning and may be uncomfortable if there is a hot spell. I also like the suggestion of staying in a smaller city like Lucca.
You could also think out of the box and consider visiting the lake region or even the Dolomites. The lake region will be busy and touristy, but summer is more of an off season for the Dolomites.
It's nice you are planning well ahead. There's plenty of information on the internet for food and wine tours and agriturismos. We prefer to travel "close to the ground", avoiding fancy digs and staying in more modest accommodations. We have the luxury of traveling off season, but even during the busy summer you should be able to have a memorable and enjoyable experience.