I just got back from Disney World about 2 hours ago. We took our two daughers (12 and 8) for 5 days there. It was the first time there for any of us.
We stayed at Port Orleans Riverside resort, which I think is considered "mid-range".
The bus service was pretty good everywhere. We never got in our car the entire time we were there.
We went with the Quick Service meal plan, but for several reasons wouldn't do that again if we went a second time. It just seemed too restrictive.
Like you, we made our plans on short notice. We used an agent. Unfortunately, the short notice meant that it was not really possible to get reservations at the majority of restaraunts where they are recommended.
Definitely sign up for a Disney PhotoCD and get a photopass when you are there.
http://www.disneyphotopass.com/specialoffers/wdwphotocdlearnmore.htm
With photopass, you can walk up to any of the Disney photographers and they will take your pic, then scan your card and you will be able to download them later. We used it alot, especially for the shots of the kids with various characters.
Regarding the characters, that was a little frustrating. The animal characters (those in full costumes) are fine. When they take their break, they walk off and their replacements return in 2-3 minutes. But with the human characters (the princesses), when they take their breaks they get pretty long ones. We missed out on 5 "human" characters in a row. The lines got cut off just as we walked up. On the 6th one, we were just barely able to get in the line before they cut the line off for that shoot.
Be prepared for a ton of walking!!!! And also be prepared to be amazed at how many people can be in one place, what lengths Disney goes to to present various themes, etc. It boggles the mind to think of the money and the behind the scenes support that goes on.
Here are my thoughts on the various parks.
MAGIC KINGDOM
Best two rides - Space Mountain and Big Thunder Mountain.
The Barnstormer might be a good first coaster for a 6 year old.
This Fast Pass tip actually works!
http://www.ridemax.com/blog/category/fastpass/
Parades get in the way constantly! They run right through the center of the park, and this can mean that to get from one side to the other you have to take a longer path.
Try to eat lunch around 11 and dinner around 5pm to avoid crowds. This applies to all of the parks. Also, get there when they open to make best use of the Fast Pass system. If you are staying at a resort, you can take advantage of Extra Magic Hours, which are basically times when the park is only open to resort guests. This is usually an hour earlier than the normal opening time, but it various by park and by day/week, so get a schedule when you get there.
ANIMAL KINGDOM
This might have been our favorite park.
Best two rides are Expedition Everest and Dinosaur!
Kilimanjaro Safaris is a must. Pangani Forest Exploration Trail was very good, too.
"It's Tough to be a Bug" was a fun show.
Camp Minnie-Mickey is a great place to knock out some pics of the characters and get their autographs.
HOLLYWOOD STUDIOS
Best two rides are Rock 'n Roller Coaster and Tower of Terror. You will definitely want Fast Passes for these. I suggest getting there as soon as the park opens and getting FP for Rock 'n Roller Coaster right away. You can then walk over to Tower of Terror and get in the standby line, early while the standby wait is minimal.
Toy Story Midway Mania! is pretty fun, as is Star Tours (Star Wars simulator ride)
Lights, Motors, Action! is a great stunt driving show! Highly recommend this!!!!
Beauty and the Beast - Live on Stage, was a good show, and Fantasmic! at the end of the day was a really impressive show, too.
EPCOT
This place was frustrating. We were told the two things we absolutely had to ride were the Test Track and Soarin', so we got there when the park opened and went right to Test Track to get our Fast Passes. By the time we got to the FP distribution kiosks, the return time was 2:15pm! We went ahead and got them, but that meant that we couldn't get them for any other rides. We went over to Soarin' after that, but the line was 145 minute wait. By the time we had used our FPs on Test Track, all of the Soarin' FP had been distributed, and the line length never went down.
Turtle talk with Crush! is really funny, and cool technology, too.
My 8 y/o doesn't even like to hear the word Epcot now. Neither kid was very impressed with it. The World Showcase section is very nicely done, but kind of boring for kids IMO. The fireworks show over the lake at the end of the day was very impressive, though!
We did the parks in the above order the first 4 days. On day 5, we went to Hollywood Studios first and rode Rock 'n Roller Coaster and Tower of Terror again, then took the monorail to Magic Kingdom and road Space Mountain, stood in line for a couple of characters, and did some shopping. The kids decided what they wanted to do again for day 5.
My overall impression? Honestly, I have no desire to go again. I am a ride guy, not a theme guy, so I can go to any number of amusement parks that have rides as good or better than the rides at Disney World. There is one park near me that has 8-10 really good rides, so with a couple hours of driving I can ride as many good rides as I rode in a week at DW. For much less $$$. But I did enjoy seeing the kids have a good time, so it was worth it to me to make one journey to Disney World. I think with my kids being 8 and 12, the youngest is old enough to remember it and the oldest is still young enough to get into it.
I'm certainly no Disney pro, but if you think of any questions feel free to send me a PM.