In Japan I like to go off the beaten path where guide books are not helpful. Daily research using the Internet becomes essential for me to navigate that often-opaque country.
I use a portable wireless router because most Japanese hotel rooms have (free) wired Internet, but no wireless Internet. I've set up my router with exactly the same SSID as I have at home. Thus my phone, tablet, and camera immediately connect to the Internet because they "think" they are at home. Pictures automatically upload from my camera to Google+ on the Web, without any fiddling.
If only Wi-Fi is available, I log the router into that signal, and still use the router as a hotspot with my home SSID. My gadgets can then work without further configuration.
A portable wireless router is one more item to carry when traveling, and that is an issue. I'm really fussy about the weight of my backpack: it must not exceed 14 pounds. Before I travel I update a spreadsheet of every item on my back, including the backpack itself, and a pair of hiking shoes (in case my hiking boots give out). The router and a short network cable weigh less than 2 ounces.
There is nothing else extra to carry. The router is powered by the same USB cable and charger I use to charge my phone and tablet.