If you want four or more ports, you're looking at something bigger than a wall-wart. I've got my eye on this new Anker product: http://www.amazon.com/Anker-Premium-Charger-PowerPort-Delivery/dp/B01D8C6ULO/

Four "normal" USB-A ports and one USB-C power port that can shove out 29W for charging a MacBook or other such gadget. That's a pretty cool solution to the "taking the family on vacation and must charge all the things with minimum travel weight" problem.