Capannori is pretty small as a center but spread out in terms of the area that falls within the town limits. I'd suggest you start out by reading the website of the local tourism office which best presents itineraries and what to see precisely in the area: http://en.capannori-terraditoscana.org/
Then of course you'll want to do day trips around Tuscany - you'll absolutely need a car to move around unless you're staying in the center close to the train station so that you can use that to get around. Lucca is a must-see, and with a car, I'd recommend heading north into the Garfagnana area and to the small town of Barga.
You don't give us an idea of how many days total you'll have but if you only have about a week, take a look at our 7 day general itinerary for additional suggestions on day trips to take around Tuscany.
Let us know if you're looking for more precise recommendations, giving us an idea of what you're looking for Hope you're enjoying planning your Tuscan trip!