As an electronics tech, I can offer a few insights.
First, the inline fuse isn't needed. USB auto adapters that are that long should have a fuse in the tip.
And at any rate, for ease of use, just tap on to the existing 12V outlets. Stock is a 15A fuse. More than enough for 3 12V taps. it'll save you a few bucks.
Check your adapter, for smart phones i recomend a 1A charger. Non smart phones, 500ma will be fine, the amperage determines your charging speed. I use my phone as a gps unit, and a 500mA charger will let my phone battery drain, slowly.
USB hubs would be usesless. New phones/ GPS units use voltage on the D+ and D- lines for charging. With a hub attached to just power, my phone isn't charging. ymmv.
Here is what i did. I found that Most outlet/usb charger like JoshMcMadMac's are only 500mA. they don't charge my phone well enough.
I tapped into the rear seat's 12V outlet in the center console. Yes those are quick disconnet T-Taps. I bought them years ago, and found them just before i did this, luck as it were, I want many more, they are so clean. see the OP for removal instructions. I just snaked the wire fron the opening under the dash to the 12v wires.
I got this on ebay for 10 bucks, 4 ports. It had an led installed that lit the blue ring up half way, my diagnal cutters removed it. The top has flaps for a clean look. the back outlets are open to the air. it's very clean looking. I bought a few small 1A USB Car Chargers, $1.75 ea on ebay. Here is the finished look
ordering the usb ports later when i have some time to figure out where i want to put them. maybe at the front of the console under the HVAC controls.