Which is a better place to stay - Florence or Small Town outside of Florence?

Ten days is a lot, why not split them? Personally, I’d want a little time staying in Florence. You’re right that there’s more to see, and the intensity is many levels higher. If I were planning on hitting a lot of Florence sights, I’d want to be able to make a hasty retreat to my accommodations for a rest.
That’s me though. With the kids in tow, you’re setting the agenda for the sightseeing. A day trip or two might be all you want/need.

Hi! Sounds like a fab trip, no matter where you choose!

That said, I am Team Florence. Lucca is small and quaint… but Florence has much more to divert the attention of tween-ish kids. And more for adults, too! You won’t run out of things to do in Florence. You might in Lucca.

If everyone is keen on just chilling, and doesn’t need lots of diversions or Big Sights to see, then Lucca would be perfect and you can take the train in to Florence for day trips, which might be a nice balance.

One Florence recommendation: La Specola. My 12 year old niece had the time of her life at La Specola. If your grand girls are at all into science or animals or the natural world, this place will amaze them: https://www.sma.unifi.it/vp-245-la-specola.html

Hi and welcome to the forums, Patricia!
I'm in Team Split' 'em up. 10 days is a generous amount of time to work with so you could easily experience the best of both worlds. The nice thing about staying in Florence for a chunk of the time is being able to do your sightseeing without train journeys on either end of the day; the treasures of the city are not far from your doorstep. Also, If someone in the group has had enough - or has forgotten something - it's easy enough to return to the accommodation to retrieve the item or chill for awhile. I'd figure closer to 1.5 hours for the rail trip between Lucca and Florence.

How much time to give each? Depends on your interests but as I'm with you as far as the wealth of things to see in Florence, I'd give that one a bit more than Lucca. But additional question? What airport are you flying in and out of, and are you flying internationally? If Florence, you'll want to put that one at the end of your trip so as to be close to your point of departure the night before. If flying out of a different city, same applies: you'll likely want to stay there the evening before. I'm not much of a risk-taker when it comes to putting at lot of distance between myself and the airport when it comes to transatlantic flights. :O)

Commuting constantly is no fun. And Lucca is a great two or three night town tops. Florence is also better connected for day tripping. I'd get the whole stay in Florence and day trip from there to Lucca and Siena at least. If you want to drive around Tuscany visiting towns, gardens, abbeys etc then a smaller town with good parking is also a good option. If you want several days of what Florence has to offer, then Florence and day trip by train and bus. we have done it both ways.

We have spent a couple weeks in Montepulciano and a week near Lucignano, and week near Siena and driven around Tuscany, but those are not trips where we wanted to spend time in Florence which is not a good day trip destination. If you want to spend time in Florence then be there.

I would suggest considering where else you may be taking day trips and look at the train schedules from either Lucca or Florence. Many times that will assist in your decision. You may find more direct trains from one or the other and that cuts down on travel time.

10 days in either Lucca or Florence is a lot, especially with a 10 and 12 year old, unless they are very interested in the arts in Florence.

Splitting is not a bad idea either. From Lucca is a quick train to Pisa to see the Tower. Also from Lucca you can find a beach town for the day. Florence offers opportunities as well to Tuscany towns.

You actually have a problem that is a good one because either choice will be great. Enjoy your trip.

We just left Florence and did a day trip to Pisa and Lucca (via a tour company). Lucca was so great and it’s definitely worth a few days. I’d do 2-3 nights there and boom the rest in Florence (or add in another city as well). We took the train from Florence to Rome and it was easy. I have an 11 and 14 year old so similar ages.

I you won't have a car to use to ramble the countryside I definitely vote for a change to Florence. You could split the trip with a few nights in Lucca or since it's an hour away by train you could make it a day trip from Florence. Florence would be a good base for other day trips as well.

You didn't mention when you've scheduled your trip or if you've traveled to Italy before. If the trip is in the next few months, rebooking might be problematic. At any rate, I'm thinking Florence will be more expensive than Lucca.

Split you stay, with more nights in Florence. 3 nights=2 full days, 4 nights=3 full days.
Besides Lucca, which should keep you busy for a full day, you can visit Pisa, which is less than 30 min away, although I don’t think you will need more than half day to visit. From Lucca also you could visit the Cinque Terre on a day trip by train (train change in Viareggio). Montecatini is also not far. Other than that, without a car, you can’t venture much in the countryside, at most you can take the Lucca-Aulla scenic train or book en organized Jeep tour to the Carrara marble quarries.

Florence itself however deserves multiple days, and commuting from Lucca gets old after a while. The Florence-Lucca train line is partially one single track only, the train makes a lot of stops, and is slow (90 min to cover 75 km). The bus is faster, but I think now it drops you off at the Leopolda station, rather than SMN, so you would need a tramway from there. Stay in Florence at least 4 or 5 nights, so you have a chance for at least one day trip to Siena.

I wouldn’t recommend lovely Lucca as the sole base for your trip for at least 2 reasons:

1) too slow and small for tween-ish girls. I think they will be bored once they’ve had fun riding bikes on the walls and climbing Guinigi Tower. Unless they keep busy by sampling every gelateria within the walls.

2) if you are staying in Lucca then you would be visiting Florence as day trippers, which means you won’t have a chance to experience its magic before the day trippers arrive or after they’ve left. By choosing a centrally located Florence accommodation, you can stroll Piazza della Repubblica and Piazza del Duomo in the early mornings and later evenings without the crowds, and you can walk (or bus or taxi) up to Piazzale Michelangelo and San Miniato al Monte before the big groups start arriving for the day.

And of course as others have pointed out, Florence has so many sights! But it’s also crowded — so maybe go first to Florence for several nights then finish up with a few nights in Lucca. By that point in your stay, even your granddaughters might welcome its slower and quieter pace.

Enjoy your trip.