Your trip is so so SO close. How exciting!
on the online check in... Here is my 2 cents. It can be a blessing or a curse. (way for me to be on the fence, eh?)
Last February, we did not do it. We checked in late (like after 10pm) I want to say it took 2 hours to check in. Why? They lost our reservation because the system went down. For days we had to go and get dp credits squared away. It was really not so magical. I feel that had we checked in online it would have gone more smoothly.
Last September, we did do it. Now, it wasn't bad. But, our room was already picked for us. I think sometimes when pixie dust is given...it is spontaneous, so I agree with All7OfUs that it may make it hard for an upgrade. Anyway...back to our room. It was not anywhere near what I had requested. I asked that they check to see if anything in a different area was available. Luckily, there was and it didnt take long to move us. Had we got in late...or maybe rooms had been filled...we could not have been moved. So in this case, I think not having our room assigned would have been better.
I guess for me... getting in late or having a specific place you want to have your room... I would not do online check in. Getting in at a normal time, hoping for an upgrade but not caring where your room actually is, I would do online check in.
Ok..so there is my "more than" two cents.