I agree with Lisa. The rate we received as AP holders was much cheaper than a group rate. I would be holding out for a special room rate, instead of the group rate.
Harder or Easier:
I would say harder than expected. I expected to have the walk to the start line as an additional portion of my warm-up (note - additional). It is a crawl to the start line. MASSIVE crowds. Heat and humidity were a factor for me. They say the course is flat. It isn't flat. There are several hills with the Contemporary being the worst. I also did not enjoy the slanted grade of the 'loop'.
If I did anything different, what would it be?
Sorry to the Elite runners, but I would bump up my expected time so I could be in a closer corral. I was honest the first time, and it worked against me.
I trained for a 16 min mile. I agree with Lisa again. 15 mins or more should be the minimum you should train for. There are unknown factors out there that can slow you down.
I followed my MFM plan and I think it is a good one. If I did it again, I would probably try the Walk/Run plan instead of the Walk plan. My stride is short and some running would help with time.
Advice for Newbies?
This is a RACE hosted by Disney World - not a Walt Disney World race. Stress on RACE, not DISNEY. I think my expectations of characters and cheerleaders and spectators was far too high. I wasn't expecting a hard to decipher sign with Buzz or Goofy or Mickey on it. I was expecting Mickey or Buzz or Goofy or Peter Pan or SOME character at each mile marker.
The water stations are not at mile markers - they are spread throughout.
Bring your own watch and track it carefully.
Carry water.
Train hard and train where it is warm. I think I would have been better off training inside in a hot gym, versus the miles I put in during 40-50º weather.
Practice with that fanny pack! I think it does make a difference.
READ Marathoning for Mortals by John Bingham. GREAT book!!
Arrive on Thursday or Friday so your body has a chance to adjust to the climate.
Skip the parks on Saturday and lounge around like we did. It will give you lots of shopping time at the Expo.

Go to the Expo on Friday if you are looking for particular merchandise. They were sold out of hats when we were there on Saturday and we arrived at 10:30 am, but shopped after registering.
I guess that's all from me.

Good luck, Kathy!