My wife and I were just there. We stayed in Varenna and were able to get to Como for a day. Being in the Lake Como area is incredible. It was like vacationing in a postcard. The only issue this time of year is the frequency of the lake ferries. It really depends on what you'd like to do in that area. If it's just a relax, checks out a few towns and villages, and explore type of 4 days then you will have a great time. Otherwise, it's worth planning around the ferry schedule a bit and not overscheduling (I axed a few items right before the trip due to the ferry).
I would suggest the Lake greenway hike which starts in Colonno (we started in Sala Comacina because that's where the ferry went). It was a delightful walk that did include some steep inclines through a town but was overall quite reasonable to manage. It went through a bunch of charming towns and we ended in Tremezzo where we bought tickets to Villa Carlotta. It was a great day. We also did the Viandante del Sentiero leg that went from Varenna to Bellano which was quite nice but much more of a true hike.
Bellagio seems obligatory so I'll suggest that you hop into Enoteca Cava Turraciolo - friendly, wines and snacks were amazing.
I'm sure you've already seen that Como has a funicular up to Brunate. It's definitely worth the up-and-back trip. I had wanted to hike from Brunate to some of the nearby mountain peaks but the timing didn't really work out to do that (partially back to the planning around the ferry schedule point above).
Have a great time!