Lake Como-Saturday or Sunday

I would NOT HESITATE to spend 2 night in Varenna at Lake Como. We just did this on the Rick Steve's Best of Italy 17 Days Tour.
Milan and Lake Como are night & day. If you like big ,noisy, pick pocket citys you'll like Milan, if you love villages, gorgeous scenery, Lake Como. Only problem could be your weather. The train from Milan to Varenna is a breeze.
Use the RS guide to Lake Como, buy the ferry pass, when docking in Bellagio immediately leave the port area and walk straight up to the top streets. at the top street these the best pizza from our entire trip! It was a little modern take out place, I think they called it Italian Street Food. Sit on some steps and watch the world go by. Then back on the ferry to Villa del Balbianello & Villa Carlotta. If you have to pick one pick the first.
Absolutely book a dinner reservation in Varenna at Quarto Pass! Tiny, family run of course and look at the photos on the walls of how this now stunning, classic, room has become. ENJOY!!!
Oh and have an Aperol Spriz & Gelato everyday!

Unfortunately, the end of November may not be the best time to visit Lake Como.

My mom and I stayed in Varenna in early October a few years ago. We enjoyed one sunny day and two drizzly/rainy days.
Upon checking out of our hotel, I overheard the owner telling another guest that her hotel and restaurant (as well as many other family owned hotels and restaurants) shut down for the winter from early to mid November till late March/early April.

If the weather cooperates, by all means take the train from Milano Centrale to Varenna-Esino (travel time about one hour) but check the ferry schedules to make sure they’re still operating.

Enjoy your trip!

Edited to add... If you do go to Varenna, make sure you buy your round trip train tickets in Milano Centrale, since the tiny train station in Varenna is unmanned.

Sit in the left side of the train for best views of the lake, and get ready to get off the train after going though the tunnel, as trains only stop for a minute or two.

Also don’t forget to validate your train tickets (date/time stamp) prior to boarding the train!

Saturday would be better. We found many things closed on Sunday (we were there in late Sept). Nov would be even worse for Sundays I'd imagine.

Train schedule might be more limited on Sunday.

Here’s Lake como ferry schedule link
Lake Como winter ferry schedule

On Sunday, driving to Lake Como, we constantly were held up by biking clubs out for a ride. If taking a train, I can’t see any difference.