While you could probably cover DL and DCA in 2 days, you'd probably be rushing around. I would allow at least 3 days. DCA can be done in a day or less. I also really like DD. It's different from the DD at WDW, and not as large, but it still has a lot to offer. I would also spend some time exploring the resorts, especially DLH and GC.
At DL:
* Have lunch at Blue Bayou. It has a magical atmosphere, and the food is pretty good too.
* The Indiana Jones Ride is my favorite there. It uses the same technology as the dinosaur ride in AK, but it's a thousand times better!
* The Matterhorn is a must ride since there's nothing like it in WDW. However, be prepared, it's often being refurbished, or it "breaks."
* The Castle is a LOT smaller, but it has it's own charm and little things to look at in the windows, etc.
* Space Mountain at DL is awesome, largely due to the music.
At DCA:
While this park could use something to give it a boost, it still has a lot to offer.
* Soaring Over California is a ride unlike anything I've ever seen, do it at least twice!
* Aladdin, I've heard it's an awesome show, though I have yet to see it myself!
* Grizzly River Rapids, comparable to Kali River Rapids in AK, but longer.
* California Screaming, a rollercoaster.
* Maliboomer, a freefall ride.
* The Sun Wheel, a gigantic ferris wheel. Some of the cars even slide around!
* Muppet 3D, just like at MGM
* A Bugs Life, like AK's
DLH has beautiful grounds, including a koi pond and waterfall. You must see the Fantasy Waters show that is held every night.
GC is my favorite resort, as it reminds me of WL in WDW. They offer tours every afternoon. I'm not sure if you have to be a guest to sign up. I also really like the Storyteller's Cafe there.
That should be a start for now, I think others will have much more to offer!