by bus or train?

Go to Rome2Rio.com to determine which trips have an all-rail option. The web site will give you an approximate time required for each mode of transportation. That will help you with some of your trips. If buses and/or trains are infrequent, your decision may be affected by the time you want to leave, and in some cases one mode of transportation (usually the bus) will get you closer to the historic district. The latter issue is covered well in Rick's guidebooks and in some others.

Chianti, I believe, is an area, not a specific place, so you'll need to figure out what town you're heading for in order to get any transportation information at all. The same with Lake Como. Are you going to the town of Como or to one of the other places on the lake?

Rome to Sorrento--163 miles south of Rome.
Sorrento to Assisi--255 miles (and north of Rome)
Assisi to Siena--72 miles NW
Siena to Chianti--it's an area NE of Siena about 10 miles.
Chianti to Florence--from Siena to Florence is about 50 miles north
Florence to La Spezia--100 miles northwest.
La Spezia to Lake Como--185 miles north (and north of Milan)
Lake Como to Venice--212 miles
To hit some of these places, it'd take a rental car. You're talking well over 1000 miles within Italy, and gasoline in this country is very expensive.
You didn't mention how much time you have?
You'd do best to purchase airfares open jaw--into your southernmost region and flying out of your northernmost region. Rome & Milan have the best international flights out of Italy.
I'd suggest skipping Sorrento (very out of the way) and taking a train north out of Rome to Orvieto where you can pickup a rental car. Then you can easily visit Assissi, Siena and some towns in Chianti on the way up to the Florence area. Turn in the car as you arrive in Florence. Take the train to Venice. Then take the train to La Spezia as I assume you are wanting to see Cinque Terre. Then catch a train up to Milan and on to Lake Como (45 mi. north of Milan.) Then catch a train back to Milan and fly out of there.

elli,

More information would be helpful. For example.....

• I assume you're flying inbound to Rome?
• Is your outbound flight from Venice?
• What's the time frame for this trip, and how long do you want to spend in each location?
• Have you travelled in Italy before? That will have a bearing on the transportation suggestions.
• Are you planning to stay in La Spezia or in one of the five towns? Which one?
• What time of year is this trip taking place?
• Where are you planning to stay on Lake Como? It's impossible to make accurate transportation suggestions without knowing that.

I presume you are not renting a car.
The answer is train in all cases, except for the Chianti hills, where there are no railways and you either drive or take a bus.
However I would rent a car in Sorrento and keep it until Florence, where I would return it. A car to visit the smaller towns and countryside of central Italy (Tuscany, Umbria) would be good to have.

Just as an aside: this is 8 moves (more if you're not flying out of Venice.) I'm curious what sort of time you're giving each of these destinations?

And as Ken noted, there are multiple towns around Lake Como so best way to reach them depends on which one you're staying in.

Eleanor, It depends on which city you arrive and depart as well as the duration of your stay in each town. Write back and we'll update our advice. I will try to help.

lake Como
Venice.

Let's assume you arrive in Rome and depart from Venice (or more likely Florence or Milan if you live in USA)
Trains, look for "Freccia" lines, also you don't have to book in advance for most trains unless you have to be someplace at a particular time such as a plane departure.

_Freccia train from Rome to Naples then local train (look for Circumvesuvia) to Sorrento. If you can afford to spend several days on the Amalfi Coast skip La Spezia/Cinque Terre later on in this schedule.
_Freccia train from Sorrento via Naples to Florence.
_Stay in Florence for a few days and visit Siena, Chianti, Assisi, Orvieto and the smaller hill towns of Tuscany either by tour or car rental if you are brave. You can do Siena and San G in one day but other than those two I would try for only one town a day. Do your homework and choose two or three.
_Car or Train to La Spezia (with optional stop in Pisa or Lucca), Stay in La Spezia and take the local train up the coast to the Cinque Terra towns.
_Train to Venice (You'll have to switch in Parma or Bologna so if you have time you can always stay overnight and see these famous food towns). You could also skip La Spezia and go straight to Venice on the superfast train (2hrs)
_Train and/or car to Milan/Lake Como. Obviously, I favor trains over car rental but for this portion I would consider a car so you can detour to the small towns along the Swiss boarder.

With this many train days you may want to contact Rick's travel advisors and talk about using a rail pass. I don't like them because of the prebooking required but they do save money. Warning they can be tricky so if this is your first time using trains you may want to stick with the buy as you go route.