I briefly mentioned this earlier upthread, but I wanted to explicitly recommend this to anyone who is based in the US but frequently travels overseas: Google Fi is Google’s wireless plan (edit: link has referral code that takes some $ off your first month).
It’s an incredible service with unlimited data and texts in 200+ countries (and calls are 20¢/min while overseas). Starts at $65/person/mo for 1 person on the plan and goes down from there, and they have pay-as-you-go plans too. So comparable to other major US carriers, but with much much better international roaming rates.
Fi is a MVNO, meaning Google doesn’t operate their own cell phone towers but rather piggybacks off of T-Mobile’s (in the US) and other partnered carriers when overseas. But it’s much cheaper than T-Mobile’s own first-party plans, especially for frequent international usage.
Using Fi means your data just keeps working the minute you get off the plane, at no additional charge. Need to call an Uber or look up Google Maps? No need to fiddle with sketchy wifi, your data just keeps working like it does back home.
You also keep the same phone number everywhere in the world (unlike SIM-card swapping). This is good for your US contacts, but not so great for your international contacts because they end up having to text your US number as an international text, which may cost them more… but nobody outside the US really uses SMS texts anyway; it’s all WhatsApp/Line/WeChat/Telegram/etc. (which you can also keep using without wifi, because of the unlimited data).
I’ve had it for maybe 10 years and the customer service has been good (one of Google’s few offerings that actually has customer service), and the service has been good in the countries I’ve tried it in (Iceland, Finland, Japan, Taiwan, the US). The data service works flawlessly and instantly, and the speeds are fine (not blazing fast, but totally adequate for normal usage).
It works great on my Pixel. It will work on other Androids and iPhones too, but depending on the particular radios a given phone has (the supported frequencies), international roaming will be slightly different from country to country – in terms of coverage and speeds, not pricing.
Overall, it’s just much simpler than having to constantly swap SIM cards and phone numbers. You can port over your existing phone number in a few minutes, or if you have a dual-SIM phone, you can add another Google Fi plan and pause/resume it as necessary (they prorate on some plans, or at most you pay for a month of unlimited). No contract or cancellation fees.
It’s one of Google’s lesser-known offerings, but it’s a really great service.