First, if you want to put a request onto your reservation, you need to do it with Member Services before you do online check-in. The online check-in screens were designed for regular hotel reservations, and don't necessarily apply to
DVC. You can only select from a very limited pre-determined list of choices, and rumor is that selections made here don't even get reviewed for DVC. Call member services and ask them to add your requests to the reservation, now.
I'll share an experience with one particular room with you. Here's an entry I made in the room database on another site:
Resort: BCV
Room Number: 566
Room Size: Studio
Room Booking Class: N/A
Handicapped-accessible: No
Lockoff or Dedicated: Dedicated
View: Quiet Pool / Canal. Room is on the corner. If you lean around, you can see part of Spaceship Earth and the Land Pavillion from the balcony.
Other Comments: Room is the last on the 5th floor hallway. It has a unique entry hall with a lot of extra room. (We stored two large suitcases on luggage stands and our Owner's Locker here.) Balcony is larger than most, and has a fantastic view. Room has an extra closet in the entry hallway. *** Room shares a wall with the elevator, which is very loud. ***
We always fight over what to put on the room request for BCV. My partner really loved this room because of the extra space, the unique layout, the view, and the extra large balcony. I absolutely hated it because of the loud rumbling sound and the way the walls actually shook every time someone used the parking lot elevator.

Now it's up to you to decide which one of us you agree with.