I decided to write this post due a silly trap that to be honest I think should be avoided in next updated of the raspbian pixel version. The last official downloadable version at the date is the 2016-11-25-raspbian-jessie.img
Here and there there are tons of posts of users that are not able to connect via SSH to a fresh raspbain installation on a PI3 of this version; I had the same problem too and tried to solve the problem thinking to the most common issues like removing the .ssh/known_hosts, check and double check the device IP address etc.
My fault is that I have not read the pixel version release notes, but IMHO the bigger fault is what they wrote in the release notes of this version. Don't forget that the Raspberry PI 3B like the previous models as well is primarily an embedded Linux device headless, it borns headless and any further element to be added to the original system - I mean keyboard, mouse, screen at least - should be considered something extra, not provided with the original hardware.
The consideration is: if I am a newbie and I buy a Raspberry Pi 3B then I install the last, modern and updated native operating system on the device, I must be able to run and access to it without to be obliged to buy or have in-house a keyboard, a mouse and a HDMI device. Absolutely not! Instead the problem is just this as you can read in the few lines above, the release notes referred to the mentioned release.
* SSH disabled by default; can be enabled by creating a file with name "ssh" in boot partition
* Prompt for password change at boot when SSH enabled with default password unchanged
* Adobe Flash Player included * Updates to hardware video acceleration in Chromium browser
* Greeter now uses background image from last set in Appearance Settings rather than pi user
* Updated version of Scratch
* Rastrack option removed from raspi-config and Raspberry Pi Configuration
* Ability to disable graphical boot splash screen added to raspi-config and Raspberry Pi Configuration
* Appearance Settings dialog made tabbed to work better on small screens
* Raspberry Pi Configuration now requires current password to change password
* Various small bug fixes
* Updated firmware and kernel
The only possible workaround is to install a previous version (I suggest the 2016-05-27-raspbian-jessie.img image) then update/upgrade the system to the pixel version that - hopefully - should not change the previous installation settings, including the ssh accessibility from the LAN.