Scenic drive from Cinque Terre to Lake Como

Wonderful question, as my young adult daughters and I will be making this same journey in a few weeks!

There are 2 basic ways to get there.
One is via the freeways A7 from Milan to Genoa and then A12 to the Cinque Terre.
The other is via the A1 from Milan to Parma, and just before Parma switch to the A15 toward Parma Ovest/La Spezia. Then you take the A15 to La Spezia. Then if you drive to Riomaggiore, just exit at La Spezia and drive the city streets across La Spezia and on to Riomaggiore. If you are going to Monterosso, then you take the A12 toward Genoa and exit shortly after at Levanto.

Either one is boring in the portion across the Po Valley, which is a flat plain that will make you feel like you are in Illinois. That portion goes from the southern edge of Lake Como (Como or Lecco, depending which branch you are staying) until you reach the Apennines mountain range (after Tortona on the A7 and past Parma on the A15.

In my opinion the A7 via Genoa is a bit more scenic through the mountains, then from Genoa to the Cinque Terre on the A12. However those freeways in Italy are largely built with lots of tunnels, therefore you will be in and out of tunnels for much of your trip through the mountainous areas and along the coast. If you drive through Genoa, it could be a good idea to make a stop in Portofino. Just exit at Rapallo and drive through Santa Margherita. Parking is expensive in Portofino (about 10 euro per hour in the only parking structure) but life is short and you can't take money with you in the afterlife.

There are other towns along the coast that you might like to drive through. For example Moneglia and Deiva. You don't need to take the freeway from Rapallo the rest of the way. You can drive on the via Aurelia (SS 1). To go to Moneglia and Deiva, once in Sestri Levante, follow the directions on some minor roads. The drive from Sestri to Moneglia is very interesting. It's through a very narrow dark tunnel that lasts forever. Since the tunnel is narrow, the flow of traffic is alternated in the two directions by stop lights at each end. Once you come out of the tunnel on the Moneglia side, it will be like emerging into Shangri-La, since the town is very quaint and secluded from the rest of the world. Just continue East through more tunnels to Deiva, then from there you need to climb back up to the SS-1 Aurelia or to the A12 freeway, from which you proceed to Levanto and Monterosso.

Since tunnels are difficult for the uninitiated, I'd go via the A15 and enjoy the mountains. Stop in Pontremoli, a lovely small town. Time permitting look at Parma, or the Stradavarius city of Cremona.