Winter prep:

Add a front fender to the road fixed gear (rear always on). Drop gearing a tooth in the rear to compensate for flappy clothes and dense air.

Put the studded tires on the single speed MTB. Drop gearing to 42X18, so that i can actually spin up the heavy, heavy tires, and for plowing through snowbanks. Put on bmx-style platforms for those emergency dismounts and tripod turns.
It's got a flap-style fender on the back, to prevent snow from building up between fender and wheel.

Wrap bars with inner tubes rather than cork.