I have a pair of Newport sandles, these...
I have a pair of Newport sandles, these fit perfectly (without socks) at 11.5 US. For the purchase of Keen shoes or boots should I go up half a size to accomodate the socks?
I'd say stick with 11.5. Socks aren't that thick, and besides sandals are sized to be worn barefoot anyway, so these are likely to accomodate.
alway try on your shoes to make sure of the right fit. even if you own the shoe currently they could still wear differently out of the box. just my opinion.
Just bought a pair of low cuts. Web site says they run 1/2 size small, but with wool socks on, an 11 fit me perfectly. My tennies are also an 11.