Over a year ago, before I even started planning our upcoming Italy trip, my sister saw a program on the castles of Bellinzona and was intrigued. This year, we've got four nights on Lake Como. The contingency planning part of me has kicked in. If we're bored/weather is bad/run out of things to do, it seems a run to Lugano and then Bellinzona might be doable. Is it too far? Too much bother? Not worth it? Stick with Lugano? I'm sure we'll make it there sometime but really, who doesn't want to help their sister's dream come true? Or it can truly be another time if that is what is realistic. I find it useful to have little seeds germinating for a Plan B. Has anyone done this? Thoughts?
I am not very much into Bellinzona, but if it is your dream, why not? - The thing you need to know, is that Lugano and Bellinzona lay on the railway line Milano-Como-Lugano-Bellinzona and up north to Zurich; actually there is a new tunnel between Lugano and Bellinzona making the trip much faster. So if you are in Como the trip is relatively fast and easy. Trains leave from Como San Giovanni station, a little up the hill.
Another option is the bus between Menaggio and Lugano. No direct experience; I see half of the buses arrive/leave at Lugano bus terminal, the other half at the railway station.
If you are not in Como or Menaggio you have to add a ferry or a bus to reach one of them, adding travel time; it may get a long hike. So careful study of timetables is necessary. The devil is in the details; ferry pier in Como is obviously at lake level but the station up the hill; also in Lugano the station is up the hill (but easy funicular trip down to centre). Station in Bellinzona is central but visiting all the castles would likely take much time and walking.
I just visited Bellinzona in Sept. when I was in Switzerland and absolutely loved it. We just made it to Castelgrande, which is the closest castle to the train station. If you get the chance to go, I highly recommend it. Your sister will love it!!!!
It is much more difficult to get to Lugano from the east side of the lake. My kids had wanted to go to Lugano last August because they thought it would be cool to say they had been to Switzerland. However, the logistics proved too challenging so we didn’t end up going. It would have been doable had we stayed in Menaggio as we had planned initially in 2020.