Trip Focusing on Rome and Pompeii: what town(s) to stay in after Rome

Let's get the low hanging fruit out of the way--you are omitting the Amalfi coast for a reason, right? I would still consider Rome + Naples + island. Maybe Procida would scratch that itch you are seeking with the hill town? If that is not interesting, then look at Pisciotta or one of the other Cilento coast towns. Last, I would look for ideas in Lazio--Viterbo is one I have had on my list.
A lot depends on the interests of the group, but I would think 20 somethings would find a lot of appeal in Naples, since there is tons to do and something for everyone.

We didn't stay in Naples, so I can't offer any opinions based on personal knowledge.

In April 2022, we used Salerno as our base for the Amalfi Coast, a day trip to Paestum, including a water buffalo farm, and for some tours to Operation Avalanche related sights. Your money will go farther in Salerno, and even more farther in Pompei. I loved Salerno, and would love to spend more time there as opposed to using it as a base. I am posting a link to the company we used to charter a boat for a cruise to Positano and back to Salerno. The tomb of the Apostle Matthew is in the Duomo in Salerno.

We are Ancient Rome freaks, and spent two full days at various "Vesuvius" sights, so it made perfect sense to stay in Pompei. I wish we had skipped the MANN in Naples, and spent another day at Pompeii. Wonderful hotel across from the Anfiteatro entrance. A lot of folks who have never slept in Pompei seem to think it's not a good choice.

My thought about rental apartments in Italy? If I was that girlfriend, I would be a lot happier in an apartment with at least 2 bathrooms.

https://www.blumediterraneosas.com/

https://www.hotelforumpompeii.com/en/

Hi
Easter this year is April 5th. Some things to consider.
Easter week in Rome is crazy and is high season, if you can avoid that week in the city, it's probably better.
Capri and Ischia are, in my opinion, more summer destinations. Going there in April, you won't be able to go into the water as it will be very cold. When you actually see how beautiful the water is, you will understand why I suggest you don't go at that time. It is better to go to that area in the summer and go on a boat.

Naples, as a city is quite fun and is very vibrant with local life. While in Naples and over in Pompeii, you probably want a tour as it will make things easier.

As for a hilltown, I think your best bet is in Tuscany. Early April is the beginning of Spring and can actually be very nice. You have many great hilltowns such as Montalcino, Montepulciano and Pienza. Here in Tuscany, you can rent a car and just go visit vineyards by yourself or stay in a agriturismo and they usually have fun activities like cooking classes etc.

As for Rome, even if you won't be there on Easter week, I highly recommend tours to beat the lines. I highly recommend thetourguy. They were great.

You could do a hill town with Orvieto. Are you planning on flying in and out of Rome? If so, its a bit of extra train travel, but you could go straight to Orvieto on arrival. Get over jetlag in a quiet location and everyone could do their own thing a bit too. Then train to Naples, and finish in Rome.

Having said that though, I would personally consider Ischia ( mainly because I 've wanted to go and haven't yet!). You could start in Naples/Pompeii, then go to Ischia, then finish in Rome.

Yep, your fantasy hilltown is Orvieto. On our most recent trip that included Orvieto, we did fly into Rome and immediately take the train to Orvieto --- worked great. We were surprised how little spoiled by its popularity it was compared to our previous visit in 2001. Your only problem is that Easter will make it more visited, but I think not "crowded" except on the weekend. More like "busy in places." So much to do in Orvieto and some of the best food we've had in Italy. Try for at least 3 nights there --- like Venice, it is a good place for getting over jetlag and very, very walkable, with interesting things to see around every corner.

For Pompeii, while it's perfectly possible to see it as a day trip from Naples or other towns, we really enjoyed staying at a hotel right at the entrance for two nights. That gets you a less crowded, less hot, early morning visit --- you just walk across the street. Also a place to collapse later in the day! Hotel Forum Pompei, I think it was.