We've stayed in both wings at the Contemporary, as well as in the Tower building.
I prefer the North Wing, for the same reasons mentioned below. If you request a room in the first corridor near the Tower building, you are just steps from the Food N Fun Center. You also are a 5 min walk from MK. The playground is also located just off the North Wing. The bus stop is also located in front of the main building on the North Wing side.
The South Wing is located closer to the pool - the pool is just off the exit doors to the wing building. This wing is closer to the convention center portion of the main building.
As far as views, with a standard wing room - you will probably get a view of the parking lot. In the North Wing - that also means facing the MK - but there are trees in the way. With a garden view - you will be facing either the pool/playground areas, or Bay Lake.
With a Bay Lake view, or even many of the pool views, you can see the Electrical Water Pageant from your room. Otherwise, you just step outside and can see it from the playground or pool areas.
You also can go up into the main building to see the castle from the observation decks. There are three - one on the 4th floor, and 2 on the 15th floor. These are great spots to watch the nightly fireworks from MK.
Have a magical trip!