Rome Tuscany Positano - May

Since they will be flying out of Rome, they need to leave Rome days for last.
Therefore the correct order is:
Arrive Rome FCO. From BOS the flight arrives certainly in the morning, therefore I recommend to take the train to Tuscany (Florence?) from the airport station upon landing.
After Tuscany go to Positano.
Lastly return to Rome for the last few nights before flying home.
They can also do first Positano then Tuscany but for sure Rome must be last.
Also Tuscany where? Tuscany is larger than Massachusetts.

Regarding beaches, the Amalfi coast is basically cliffs. It’s a beautiful place with turquoise crystalline waters but not really beaches, it’s rocky cliffs, except for some pebbly coves. If by beaches they intend Florida type sandy beaches there are none in the area. Google Image search “Amalfi coast beaches” and you will see what I mean.
These are some examples.
Positano is very quaint and scenic, therefore perfect for a honeymoon. They also have boats to Capri if they care about taking a day excursion there. The most famous hotel is “Le Sirenuse”, if they want luxury, but there are many others for less money (the place is expensive overall).

If your friends can afford it, they might love staying in Ravello. I thought the Villa Cimbrone was the most beautiful place I have ever seen. Ravello would be Jackie Kennedy and Positano would be Kim Kardashian.

https://www.hotelvillacimbrone.com/

My husband and I aren't honeymooners, but we loved the day in April 2022 when we chartered a boat to cruise along the Amalfi Coast. The charter company we used may not work for your friends, since they are based in Salerno. But here is the link:

https://www.blumediterraneosas.com/

You are a good friend to be helping with the plan!

I will agree with Roberto that the order needs to be Tuscany/Florence> Amalfi Coast >Rome. They don't want to be on the coast the day of an international flight back to the US.

It looks like they're planning on spending the better part of week on the coast? Positano is not very big, and offers little to do...which might be fine for honeymooners with little interest in leaving their accommodations/room very often. It does have a large beach (Spiaggia Grande: google up pix) but otherwise I'd choose a different location. Ravello? Too far from activities they may wish to take advantage of, such as Pompeii or Capri, and not on the water. It looks like they're planning on spending the better part of week on the coast?

I would suggest that they spend at least 4 nights/3.5 days in Rome. It takes that long just to scratch the surface.

"Tuscany" is a broad subject. If they intend to use public transit to get around, I'd suggest basing in Florence (capital of Tuscany) and taking an escorted wine tour one day, and indy exploration of, say, of Siena on another. Or just the tour and leisurely exploration of Florence's historic sites. If taking 2 day trips, I'd spend at least 5 nights in the city, especially if the first night is on arrival day, as that would only provide 4 FULL days for the city and the region.

Your friends would be warmly welcomed on this forum themselves if they want to be included in conversations about their trip. You might encourage them to sign up?