When you are within 10 days of your trip, you can use online check-in. I accessed online check-in by going into 'My Vacation' on the Disney website, but I know there was also a link in an email I received, as the trip got closer.
Basically, you just verify information and enter your credit card information (if you want to be able to make charges with your KTTW card). It only takes a few minutes.
There is not a space to make specific room requests. If you want to do that, you need to call Disney and ask for it to be noted in your reservation. If you do have room requests, they will not show up on the online check-in page.
We used online check-in in June and it worked well, for us. The regular check-in line had quite a few people in it. The online check-in line didn't have anyone in it. We were able to walk right up to the counter.
Since we did online check-in, our package of information was ready to go and our KTTW cards were already printed. I think I was at the counter less than five minutes.
I would use it again.
Have a happy trip!