Need to drop one: 1 day Milan, 1 day Lake Como, 2nd Day in Florence

As of now were planning to arrive in Florence at 10am, and stay there until the last train at 7pm. to Milan (on a Sunday), We would then stay at a friend's house in Milan to do a Day trip to Milan, and then another one to Lake como. The advantage here is that I see all three, and without hotel costs. Though I'm sure 8 hours is nowhere near the amount of time needed to get a good feel of Florence, so I'm thinking about taking a hotel that night, to then take the next night train and cut out either lake como, or Milan. Which option do you think I should cut out? Thanks!