I purchased a 500 this summer and think it is a fun bike.
The following is an overview of the local Kawasaki winterization presentation they made for bikers last month.
They highlighted the following.
Remove battery - they can freeze - a $40 battery tender will pay for itself in a longer battery life. ( I did not do this I have a new high tech battery tender that I keep connected to the battery all winter)
Over inflate your tires by 10 - 15 lbs - they will loose pressure over the winter and it is better to keep the side walls properly supported.
Plywood under your tires - don't really have to raise the wheels off the floor for the short winter storage - use centre stand if you have one.
Add stabalizer to a full tank - drain carb bowl even though stabalizer added to the fuel.
Change oil (ensure engine has been running and warm - to ensure impurities do not settle prior to draining) and filter. Did not think there was much advantage in changing oil again in the spring.
For mice protection use Bounce sheets. Place strategically in and around the engine particularly protecting the air box and electrical wiring. Also seal exhaust ports and add Bounce sheets.
Put away a clean bike.
Cover with a breathable fabric.
Do not start the bike periodically during the winter.