I've just added a small flat to the wall surge protector with two outlets and two USB charging ports to the travel kit (we leave on vacation in 11 days). It was on clearance at WalMart. The package also includes a car adapter for a USB cable.
I also have a similar but wider flat to the wall electrical device with two USB ports, but it is not a surge protector, so we won't be using it for a computer. It can still be used to set up a second "charging station" for cell phone or tablet, though.
We're taking a trip in November to meet up with family members at our time share - there will be at least four and possibly five or more cell phones (two of them smart phones) and an unknown number of other deviced (tablet, Kindle, Nook, etc.) since I know that at least two people will be getting new phones by then (possibly more - depending on if a couple of older phones still work). Or recharging external power banks - smart phones can chew through a "full charge" in an amazingly short time - having a "spare charge" stored in a pocket or purse comes in handy (and I don't even have a smart phone)!
A similar adapter would let you plug in a CPAP and a cell phone or digital reader/tablet at the same time.