Wow, you will have a fabulous trip. Staying at GC means you do not have to worry about getting MM entry on your park pass. With any luck you may be able to see some of WoC from your room, as many of them look out over DCA. You also have a direct entry into DCA from the hotel, which is very convenient when you get soaked on Grizzly River Run! This is the same ride system as Kali but a different theming and a lot more drops and thrills than Kali. It is one of my favorite rides, but I am always the one who gets soaked.
Have your kids ridden Rock n Roller coaster or Everest? If they like those, then I think that they will like Screamin'. I highly recommend this ride- it is a great coaster. It is one of the longest coasters in the world and gives a fun, enjoyable ride. I have ridden extreme coasters, but I prefer coasters like Screamin'. You can also see the progress on Carlands from the top of the highest hill. I should also alert you that our Space Mt. is not the same as the one in WDW. It has been changed since you were there last. It is smoother and faster. I found the WDW Space Mt. not as thrilling.
So here are some differences to keep in mind. Unlike WDW it is very easy to park hop at DLR. The main entrances to DL and DCA are directly across each other and it takes less than five minutes to walk between the parks. The FP system in one park is separate from the FP system in the other park. So if you are in DL and are about to take a midday break you can pull a FP in DL then walk out the front gate, cross over to DCA and use your ticket to pull a FP for Soaring (or any other FP ride in DCA) on your way to the GC entrance in DCA.
In the past, you could always count on DL being more crowded than DCA. So you would start in DL in the morning (it usually opens earlier) and when it got crowded you would move over to DCA. It is unknown how much WoC will affect this crowd pattern. As a mentioned in my earlier post annual passholders have a huge impact on crowds in DLR whereas it is a non-issue in WDW. Many local annual passholders have no problem staking out a parade/Fantasmic/fireworks spot hours ahead of time. I don't think Disney is going to allow this for WoC, because the park will become completely clogged.
Don't assume that a ride will have a FP because it has one in WDW. Most notably, neither Peter Pan nor Toy Story Mania have FP. As in WDW, Peter Pan is a very popular ride and develops a line quickly. So hit it first on your MM entry. My MM order is
Matterhorn ( twice)
I did not include Snow White, Castle walk-through, Pinnochio, or the Carrousel b/c these can usually be done later without significant wait. I did not include Casey Jr. Train or the Canal Boats as they are usually not open for MM. I have not been to DL in June for some time, so they may have more rides running during MM for you. But you do not want to get on a ride that takes 20min during this hour. The Canal boats and Nemo each take at least 20 mins -Autopia is probably 15 mins. You can do several rides in that time span. You will not be able to pull a FP until regular park opening time. I try to pull one for Sp Mt. as soon as I can. You will see that Autopia also has FP. Unfortunately, the FP lines joins the standby line, pretty far back, so it doesn't really help you that much. I never waste a FP on Autopia, but this line can get long and it is mostly uncovered, so if your kids want to ride you should do it in the morning or late at night. AstroOrbiter can also develop a long line. You will have more than one MM so you can do a Fantasyland focussed MM and a Tomorrowland focussed MM. I am usually staying off-site so don't have that luxuy.
I realize that your kids my be too cool for Dumbo, but my DD16 has to ride it once every trip , so I left it in and you can skip anything that you are not interested in. Casey jr and the Canal boats both go through Storybookland and both are park originals. I have a strong preference for the Canal boats. It was one of Walt's favorite's and- especially if you are a gardener- a delight. The boats meander through the land while the train zips around the perimeter. They close this attraction during the afternoon parade, so a good time to get in line is right after it gets reopened. It is also charming at night.
Don't miss Indy, Pirates, Mr Lincoln, Billy Hill, IASW, at DL. Take the Columbia or the canoes (or both) around the Rivers of America. See the original( and completely vintage!) Tiki Room. Capt. Eo is back. It is probably your last chance to see the original version of Star Tours as it closes in July in DL and later in the year for WDW. Make sure that you see all segments of the grand circle tour of DLRR. The exhibits from the World's Fair are between Tomorrowland and Main St. Station. Note the lamp in the window for Walt in the Firehouse. The Mad Hatter plays musical chairs at Coke Corner around 2-2:30. Lots of live music in the park. If you see an elderly man playing an electric guitar in NOS, know that he was playing music in NOS the day it opened and knew Walt. Do NOT miss Aladdin at DCA - you might want to see it more than once. It lasts about 45 minutes so it is also a good way to take a break from the heat and get off your feet.
Are you eating at the DLHotel for one of your meals? There is lots of memorabilia/photos in the lobby hallways to peruse. Stroll the grounds as well.
Try the beignets at Ralph Brennans for breakfast (send someone to get a bag of them to bring back to the room).
DLR has a lot more crowd control procedures than WDW. Talk to castmembers handling crowd control as to what procedure will be used for the nighttime entertainment that night. People may be seated in the street at the Hub waiting for fireworks to begin, but at somepoint the crowd may be told to stand and to move forward. This changes everything and maybe not for the better as far as your sightlines go. One night, however, I was expecting this to happen, and it didn't. We were allowed to watch the fireworks seated on the ground. Also know that there are crowd control traffic patterns on Fantasmic nights, foot traffic heading to the RoA will go in through Frontierland and traffic leaving the RoA will go via Adventureland.
Ok...Probably much more than you needed, but am trying to get you comfortable with fact that despite crowds for WoC, you will have a fabulous time. You are staying for so many days that you can relax as far as seeing everything.