Your first time...how exciting! Don't worry too much about the crowds, as long as you are willing to get up early at make it to the parks at opening time. That is really my best advice overall. We were there over spring break, which was packed, but we never had to wait longer than 30 minutes 2 times the whole week. I never thought I would do this, but we left the parks some days around 12 when the crowds got bigger and we relaxed at the hotel, then headed back later in the day. Since we were at the parks early, we were able to get through a lot of the rides that people were waiting 30-60 min for. Be sure to use fast pass as you go too. You may find that your family may choose to separate at times so the 9 and 6 year old can take rides that the 2 year old can't...I don't know if that is necessary since we were only traveling with a 22 month old so I am not speaking from experience. We did not book any meals, because I did not want to stick to a set schedule, which was good with a young one. I do love the character meals though!
here are a few of our park favorites:
MK: Winnie the Pooh (all of fantasyland for the 2 and 6 year old), Jungle Cruise, Philharmagic, Buzz Lightyear, The mountains, Country Bear Jamboree, toontown for character pictures, the MK railroad
dole whip for a snack, and fireworks while sitting at the Terrace (an outdoor eatting area right outside of tomorrowland...great view and great seats!)
AK: The safari (go here at park opening, since there are no lines and the animals are very active) Don't miss the walking trail at the end with the Lowland Gorillas. Expedition Everest (fastpass this one early...send 1 person to get passes while everyone else rides something else)
The festival of the Lion King....do this just after the safari, so the crowds aren't too big. also, try to sit to the right when you enter the show, so you can be close to the exits for pictures with the characters, which are right outside the show.
MGM: Little Mermaid (magical!), the Muppet 3-D show, Rockin Roller Coaster, tower of terror, Who wants to be a millionaire (may be tough for 2 yr. old though to sit through) Fantasmic
EPCOT...hmmm...tough with a 2 yr. old in my opinion. They have to be out of the stroller for most exhibits, so it is a long day. The young ones will like the living seas and Imagination. We left soon after that this time b/c our son had a rare meltdown there.
Most of this advice ships tha big rides...we missed a lot with the 2 yr. old, but it was great through his eyes, for sure! Have a great trip!