Mobile Phone Plan

Is your priority ease of setup, reliability, or cost?
How many need data?
Do you need to be reachable with your US phone number? Sometimes you need it for MFA if you're accessing accounts for anything, including tickets to sites.)
Recommendations will vary based on your priorities.

So many questions, so many options. With little to go on all I can offer is that if you want phone/data service in Europe that is comparable to what most of us have in the US with not additional hassle or thought .... just pick it up and use it .... then open a TMobile account.

Are needing text, calls and data for 7 phones? Can you get by with WiFi and WhatsApp for some of your phones?

Apologies for the lack of detail. We're planning on only 3 phones. All will use SIM cards. Not too concerned with setup, although one never knows. Not sure how much data is needed, but I think the 20GB plans I've seen will be more than enough - mostly we'll be using wifi. We do not need to be reachable at our US phone #s. Needs to be EU coverage.

Another satisfied Tmobile customer here. Just be sure you get a tmo account with the international roaming.

We do not need to be reachable at our US phone #s. Needs to be EU
coverage.

The service I use has worked flawlessly from Kyiv to London to Rome to Tirana, Albania .... Just this past week, all over Montenegro and I use it daily in Hungary. Its called TMobile and my US number works if I wanted it to or not.

The only word of caution on European sims is if you need to get into a secured US Website. That would be some government websites like my Texas Drivers License, but then there are a few you wouldnt expect like the Orvis site. You never know who has blocked other than US IP addresses. With the TMobile I dont have to worry about that.

I have used Ubigi for data in Spain/Portugal and in Scotland. Very inexpensive. Am going to France shortly and will get it again to supplement Consumer Cellular international roaming. For calling and texting I will use WhatsApp if possible.

Just finished 10 days in France with t-mobile. Flawless to home and to group members with international data plan.

I recommend checking esimdb.com. it's a website that aggregates eSIM plans from a wide variety of providers.

It’s pricier, but Airalo has a global eSIM plan that gives you all the above and that you can get for 30 days or 60 days. If I did this, I might do it for only one phone, since I would need more data than it comes with. But it is very easy to top up. So you could do 30 days, then top up with 7 days (the least).

Or if your phone accepts physical sims, you could just get an in-country SIM card when you arrive.,

My main phone is Tmobile, but I like to carry a spare phone. On it, I use a Roamless esim. It's true Pay as You Go. That means you charge your "wallet" with $10 or $20 (I use Paypal). There is no monthly charge so the wallet balance stays forever until you use data. Then you pay $2.45 per Gb. in most countries, much more in a few Asian countries. It is data only. Overall, Roamless works in 200+ countries. I also use it in the US, in a few places where Tmobile has no coverage. Very easy to use their app to "top-up". And within the app, you can make free outgoing phone calls to anywhere in the world. It allows wifi hotspot useage. Only downside is that if you use a lot of data, it might cost more than some other low-cost esim plans.

You do not say what your current plan is, but having traveled frequently, my wife and I have Android phones with Google Fi for service. They work about anywhere at no added costs, except if we make international calls, and even those are a relatively tolerable rate.

Recently, with upgraded phones, we augment coverage with a local SIM through Airalo, since when we travel we use a lot of data. With Fi, we pay $10/Gig, but I can get 20 Gigs on an eSIM for less than $30.

Our phones have the ability for one physical and one eSIM, or 2 eSIMS. Once both SIMs are installed, you can also chose which SIM is used, independently, for Calls, Texts, and Data. So I set the phone to use data via Airalo, but calls and texts through Fi.

We do not need to be reachable at our US phone #s. Needs to be EU coverage.

More and more though, you need to be reachable for alerts from Credit Cards, if your card has 3DS (I recommend it) for purchases, for 2 factor authentication, and any emergency contact. Use Whatsapp to communicate with hotels and others in Europe via your home number.

More and more, though, you need to be reachable for alerts from Credit
Cards,

Paul is correct on that. Not a week goes by when I dont have to input a texted code number to log into something or recover a lost password. From time to time, like with my bank, calling from the cell phone number is part of the identification process.

You don't need to carry cash in Europe and you don't need your US phone number to work in Europe ... but from time to time both can be extremely convenient.

I have been Orange eSIMs that has 31 day options with talk, text, and data in Europe. It also has some international calling and texting features.

We have been happy with the Orange Holiday eSimm, too.

I recently used Airalo between England and France, no issues. There's a variety of data plans available and can easily bump-up or, top-up your data as your initial plan gets used-up; from 1GB to larger 100GB & unlimited plans are available..
One bit of consideration, if you plan to use your device for route-finding/directions, you may want to bump-up your data availability. Driving through the country-side and using the map apps to guide you along, can use-up your available data, nothing like social media/video driven apps but, just be aware.

Another happy airolo user here, but my husband uses his international plan (Verizon). That way if we need a 2 factor authentication or to call the credit card company (which has happened more than not), we can do so.

Maybe have one person on an international plan and the other users on a sim? Also, if a monthly plan is available, maybe you can wait a day or so to "engage" the international plan so it is only one month? Just keep the phone in airplane mode and use WIFI only for WhatsApp and messaging.