I am also a WDW vet but have been lucky enough to have been to DR twice now (third time will be next month!). As a WDW vet of course you want to hit the rides not at WDW or the ones that are markedly different. So my list kinda reflects that.
DLR -
Paint the Night parade - it is the MSEP on steroids. I love the MSEP and was super excited to watch PtN, it did not disappoint.
Pirates - longer, more detailed than the one at WDW.
Mr Toad - was very upset when they took it out of WDW so this one is more of a personal preference.
Indiana Jones - so well themed! The queue, the ride, really liked this ride. It was down for most of our stay.
Haunted Mansion - granted I've only been during Halloween, I love the NBC overlay.
DCA -
Oswald - near the park entrance. I disbounded as him and he and his handler got so excited. I guess he gets little love in the park.
RsR - yes, it is as good as everyone says.
Grizzly River Run - so much better than Kali River Rapids. It feels like an actually a ride, not like they just dump water on you.
WoC - I am not much for shows, especially if you have to wait forever for a good spot, but this one was good. Different than any at WDW.
Mater's Junkyard Jamboree - DD loved this ride, she could not stop laughing.
bonus - Soarin' - yeah it is the same but it is a different experience when you are actually in California
DCA is a beautiful park. Carthay Circle has great food (the apps alone make an awesome meal) and the dining room is classic Hollywood. The Cozy Cones in Carsland have mac n cheese served in a bread cone (yum).
At DLR I inhaled several beignets (and then went to DtD and got some more at the Jazz Kitchen). Lunch at Blue Bayou is a must do (even if just once since it is not cheap). Sat by the water while PotC boats go by.
At DtD - Ralph Brennan's Jazz Kitchen had the second best (after Carthay) food we had all trip. Sat outside in beautiful weather and watched Halloween party goers go by in their costumes.