Crowds will be decent, as most schools won't have gotten out yet. And weather will be nice. I see you're from Texas, so you will love the weather. It will probably be warm (80s-90s), but not muggy at all. Very nice weather for theme park touring.
Now even though the crowds won't be huge, you still want to make it to park opening each day (which will probably be 9AM every day except Sunday which will be 8AM). And early entry (because you're staying at the GCH, you can maximize your EE privileges) will be offered on the 2nd, 3rd, and 5th of your stay, which means on Monday, Tuesday, AND Thursday, you can enter DL an hour before other people. Having 3 EE's is very nice and here's how I suggest you use them:
Doesn't matter the day:
1 EE- Fantasyland (Peter Pan and a ton of rides that WDW doesn't have such as Alice in Wonderland, Mr. Toad, Pinocchio, and Matterhorn.)
2 EE- Nemo. This one ride (unique to DLR) will probably take up your entire EE, but since you have multiple, it is ok.
3 EE- Tomorrowland. This is a good time to ride Space or Buzz repeadetly with no lines for an hour. However, if you're really tired, using your 3rd EE could be overkill. I'm sure you will be able to ride Space and Buzz some other time during your trip.
Also don't miss Indy, Matterhorn (already mentioned), and California Screamin if you're into thrill rides. They are unique to the DLR and are all great. Some other unique rides include Storybookland Canal Boats and Casey Jr. Circus Train in Fantasyland, Roger Rabbit's Cartoon Spin in Toontown, and Monster's Inc. at DCA. You will be very impressed with Buzz, Pirates, Autopia, and Tom Sawyer Island/Pirate's Lair because IMO, they are much better at DL than MK. Rides like Star Tours, HISTA, Bug, Muppets, and Soarin are the exact same. Unfortuneately, I believe IASW will be closed most of the 08 year, which includes June so you won't be able to see the original version; However, probably everything else will be open.