Italy Itinerary Check - Also Amalfi Coast or Cinque Terre/Lake Como?
 

This is what I had for my itinerary. Just a note: I’m in my early 20s and traveling solo. So I do like a faster pace.
Day 1: Land in Venice Marco Polo International Airport


Day 2 - 3: Venice



Day 4: Leave Venice for Florence, maybe a quick stop in Verona?



Day 5-7: Florence (day trip to Siena, the rest are Florence)



Day 8: Sorrento, half a day in Naples (maybe see the archeology museum). I kind of want to somehow fit in Pisa into this, but probably too rushed.



Day 9: Pompeii/Herculaneum



Day 10: Amalfi/Positano



Day 11: Path of Gods hike



Day 12: Rome



Day 13: Rome



Day 14: Rome



Day 15: Rome



Day 16: Leave

I also kind of wanted to see Lake Como and Cinque Terre. But I can’t fit Amalfi, Lake Como, and CT. Any advice on which to prioritize for a first trip to Italy?

I think it's basically fine. If you're in your 20s, I think the Naples/Amalfi Coast/Sorrento area will offer more than either the Cinque Terre or Lake Como.

You can visit Pisa from Florence. You might want to add a day to Florence, taking it from somewhere else, depending on how much you want to see in Florence and Pisa. It only takes a bit more than two hours to get to Florence from Venice, so if you leave Venice early, you really have nearly another full day in Florence.

I'm a little perplexed by days 8 and 9. It takes about 5 hours to get from Florence to Sorrento, so you really wouldn't be able to do a stopover in Naples to visit the Archeological Museum. If you want to visit Pompeii, Herculaneum, and the Naples Archeological Museum, I suggest you spend two nights in Naples rather than pushing on to Sorrento, requiring you to loop back to Pompeii and Herculaneum. Then you could still arrive in the Amalfi Coast on the 10th.

Take note of what days of the week you're in Florence, and check your sightseeing list against the open days/hours of everything. Most of the main sights are not open every Sunday and/or Monday, so if your only days in Florence happen to fall between Friday and Monday you might have to decide on your priorities... Florence or Siena or Pisa.

You could make a short stop in Verona on the way from Venice to Florence, but as you plan the logistics for that day don't forget to include time spent storing and retrieving your luggage in Verona.

Before you settle on the idea of traveling Florence-Pisa-Naples-Sorrento in a single day, look at the train schedules and work up an hour-by-hour plan for the day. Don't forget to include time to store and retrieve luggage in Pisa. If you want to climb the Leaning Tower, you need to make a timed reservations. You can't carry any bags or backpacks when you climb. FWIW, if I had to "find" a half day somewhere in this itinerary, I'd choose Pisa over Verona. But that's me.

Were you planning to stay in Sorrento while you visit Naples, Pompeii/Herculaneum, Amalfi/Positano and hike the Path? Following on bvlenci's post, it might make more sense to stay a couple of nights in Naples and then a couple of nights somewhere on the coast rather than Sorrento. If you split your nights between Naples and the coast, consider traveling Florence to Salerno and then to a town on the coast. After your days on the coast, head to Naples and stop at Pompeii along the way. There is luggage storage at the entrances to both Pompeii and Herculaneum.