The Ceptics travel adapters are good hardware for American world travellers. They combine a USB charger with a passive plug adapter for AC. Carrying one of those is enough for me for a multi-week vacation, providing plenty of charging for my laptop, phone, tablet, etc. No need for extra chargers or adapters. They come in different models for European, Australian, UK, etc sockets. They also make a universal adapter kit but it’s a lot bulkier.
You’d think a passive AC adapter would be a simple thing but a lot of them suck. Ceptics’ solution makes for a plug that sockets reliably and firmly. And it has a reasonable workaround for polarization and universal 3 prong grounding. You may not get a true third wire for ground (ie, the Type C European plug is only 2 prong) but at least your laptop charger will physically plug in and function.
The Ceptics’ USB charging works well. USB charger quality varies greatly. I can’t really judge what’s inside the Ceptics charger except to say that it never gets warm and seems to provide the right magic signals to charge my iPad quickly.