The biggest perk of staying at the DVC villas at the Grand Californian is their private rooftop viewing area for California Adventure's "World of Color" lagoon show, which opens this spring. So they should definitely take advantage of that!
Also, the hotel's Napa Rose is one of the best restaurants in all of Southern California, so that might be something they'd like to try.
There aren't a lot of special/private event options at
Disneyland, but I guess they could do the Fantasmic Dessert Buffet inside Disneyland. You get to sit in a reserved seating area and eat ice cold pastries

cutie

. It doesn't really cut out waiting in line, though, because the only way to get the good seats is to show up and wait in line an hour before check-in starts.
California Adventure will be having its version of Mickey's Not-So-Scary Halloween party at that time - that's something to do. What else...?...If they like swing dancing, there's a live band on Saturday night at Carnation Plaza inside Disneyland.
They can get Just Married buttons from Guest Services and wear the bride and groom ears....
The Blue Bayou is a romantic place for a meal...
There's a Mandara Spa at the hotel...
OK, I'm running out of steam...
