Walk!! It takes about 8-9 minutes to walk from MK to CR...the path is well lit and very pleasent, unless it's raining. It basically runs underneath, more or less, the monorail tracks. If you take the monorail from MK to CR, it will take you several minutes to get to the monorail platform. Then, you may have to wait awhile for the next monorail to arrive. It could take you a total of 25 minutes to get to CR from MK. That's why we always walk.
When you are ready to go back to MK...do NOT take the monorail if you are in a rush. The MK will be the last stop for you...it could take over 30 minutes to get from CR to MK..especially if you have to wait for the monorail to arrive at CR. It basically takes about 25 minutes to make the complete circuit around the lake via the monorail. You will be much better off walking back to MK if you are short of time.