NJ to Italy-June 24-July 2

First, maximize the number of days, as much as possible. With the dates given, three locations max .
I'd suggest Venice, Florence, Rome. You don't have enough time for the AC. Beaches in Italy just aren't as nice as in the US- they are beautiful to look at, but the beaches are made of pebbles . Maybe you can get your water fix from Venice, which is so unique and charming. The island of Lido does have a beach. And- Flying into Venice is easier than flying out.
You are actually late to secure lodging, especially for your number of folks, so I'd firm up an itinerary asap. The availability of lodging may influence your destinations, especially since you want to use points.
You didn't specify your interests - that would help with recommendations.
Perhaps an RS Guidebook would be a great resource for suggested itineraries. Also, Search here on the Forum, there's hundreds of posts with very helpful info.
Have a great trip!

It’s the perfect amount for Florence and Rome, so a beach stop will be a compromise. Somewhere between those two will be the only option for a coastal stop time-wise, so that helps narrow it down for you. I’d say research that area and see if you still want to do it.
There might be a site or app where you can determine how best to use those points, but I’m clueless. Try the individual sites to get a better sense of how they might be utilized.

With only 5 or 6 nights you don’t have time for much-2 locations, maybe 3 if you can increase to 7 or 8 nights
It will be hot

Consider just Rome-fly RT from PHL or EWR
You could do a day trip to Amalfi-it will be a long day! just to see the area or day trip to Florence

American also flies direct RT Rome from PHL
We like the PHL airport a lot- much easier than EWR!
45k points is not enough for a flight though

There are no direct flights to or from Florence/US

I would be sure to fly in and out of where you want to be- even if Milan is less expensive- you don't want to waste time/money getting from Milan to wherever you are going with such a short trip.
You could fly to Venice- 3 nights there then to a Lake for 2 nights then to Milan 1 night for departure since you must be in your departure city night before.
Lake Maggiore/Stresa is close to MXP so if you stayed there you can get to airport next am- direct bus- no need to stay in Milan
Both Venice and Stresa are “water” locations

(American flies direct to Venice from PHL and home from Milan- search "multi-city- not 2 one way tickets)

I don't know what IHG points are, but guessing a hotel chain. Since you have have the most Chase points I would use those for as much airfare as you can. I think Chase let's you pick the airline, so you just need to determine the airpports, depending on what airline you prefer. EWR is United, and PHL is American etc. We do choose Milan often, and we are always on United or Lufthansa.

Rome and/or Florence is the biggest question. They are so different.

When you say beach town, do you mean a place to view the water or go to the beach? I love the beach, but I don't go to Europe to go to the beach. Water views could be Venice canals, Lake Como or the Med.

I would suggest Milan-Como-Rome. Or the reverse. Or substitute Venice for Como. Venice is just a few hours from Milan by train.

It is pretty hard to get non-revenue air tickets these days, especially at the absolute peak of summer travel time. I suggest that you bite the bullet and buy the tickets sooner, rather than later. Since this is your first post on this newsboard, please tell us about your leisure travel experience in the past. Have you bought or libraried Rick Steves Italy yet?

Have you been to Europe before? Where did you go. Is this trip really worth it for 7 or 8 nights? Especially if you are on a budget, you are going to have an early return departure, making you sleep in the airport's city on the last night. Beach towns don't have airports.

I agree that east coast US beaches are more attractive than average Italian beaches. I wouldn't go to all this trouble to sit on a beach, but that's personal preference. Our first trip to Italy (1988 ish), a few years after getting married, was Rome-Florence-Venice, approximately two weeks. It's hot in Italy in the summer.

https://www.ricksteves.com/travel-tips

My thought would be to fly RT to Rome. You should be able to get direct flights hopefully using as many points as possible. My suggestion would be to land in Rome and then take the train to Termini then head down towns the AC for a couple of nights. It looks like there are Holiday Inn options in Naples and Salerno that would allow you to use the IHG points. Though I have not stayed in Salerno, others on the forum have suggested it as a potential base for a couple nights near the AC. You may not be on the water in that hotel, but you can easily visit. From there, you can head back to Rome for a few days. It appears most of the hotels no longer had rooms available on points, but that may change as you get closer to your travel dates. I would suggest booking other refundable or free cancellation options as backups.

Given the length of your trip, the other option would be staying in Rome and day trips to Florence and/or the AC. I know others have had poor experiences with Walks, but we did day trips to both locations with them from Rome a few years ago and had good experiences. They were definitely long days, but doable.

As others have mentioned, you will want to spend the night before your return flight in the departure city so if you aren’t able to find good prices on multi-city tickets, I would suggest going to the furthest location and then working your way back.

Regardless, I suspect if you want to use points, you will need to book sooner rather than later as non-revenue seats and rooms are limited these days.

You will have to figure out how and where you can use your points.

Travel for as many nights as you can, even just adding 1 night makes a difference.
Count your trip by number of nights on the ground in Italy.
Leave 6/24, return 7/2 is 7 nights.

There are lots of flight options from PHL or EWR to Naples, Rome, Venice, Milan

American flies direct from PHL to NAP, FCO, VCE, MXP
United flies direct from EWR to NAP, FCO, VCE, MXP

Accommodations will be limited on AC so you will need to firm up itinerary soon. Your itinerary may end up being based on where you can find lodging.
Look at Salerno (has a sandy beach) as well as the AC towns.

If Rome and AC are priority:

Fly to Naples
Salerno or AC town 3-4 nights
Train to Rome
Rome 3-4
Fly home

If you fly home from Naples, you’ll need to stay in Naples night before departure (this is why I would fly in to NAP)

Fly to Rome
Rome 3
Train to Salerno/ferry to AC town 3
To Naples for 1 night
Fly home