Since this is your first visit, I would wait until your first day to decide whether or not you really need park hoppers. As a frequent visitor to the park, I am used to going back and forth, but you may want to spend the time concentrating on the park you are visiting instead of thinking that since you paid for the hoppers you need to make those tickets worth the price. It's nice that you have four days because you can spend two days in each park. Having said that, I would do Day 1 -Disneyland (of course), Day 2 - California Adventure, Day 3 - Disneyland, Day 4 - Park Hop to revisit favorites. The candy canes are special, and good, but not a 'must-do' in my opinion. However, if you're looking for unique Disneyland experiences, this is one of them. You have to weigh whether or not you want to spend your time waiting in line for a wristband to get a candy cane, or if you want to experience the park itself.
These are just some ideas:
Disneyland - You might consider riding the train around the park to get a feel for the different lands. It's very different than the one at Walt Disney World. When you ride it and hit New Orleans Square you'll hear the telegraph sounds of the beginning of Walt's speech on opening day. You'll also get a view inside Splash Mountain as you go through. If you are a Star Wars fan, you might consider starting your day in Tomorrowland on one of the days and going on Hyperspace Mountain first thing, or getting a fast pass for it. When we went last Friday, we got a fast pass for Hyperspace Mountain, and then got in line for Star Tours, and that worked out for us. Attractions to ride early in the day are Haunted Mansion Holiday, and it's a Small World holiday - don't miss it's a small world. It is different than Walt Disney World, and there are Disney characters that the other park doesn't have. Your kids will have fun spotting them on the ride. The Elvis on Lilo & Stitch's skateboard is only there during the holidays. Indiana Jones also gets a long line, and you should all go on that. It's similar to Dinosaur at Animal Kingdom, but not scary, and much better experience (in my opinion).
On Main Street, I always enjoy riding the horse surrey in the morning, but you just might want to walk and drink in the atmosphere. Of course, be sure to look at Walt's apartment above the Firehouse. The line at City Hall might be really long, and if so, you can try one of the stores for 1st time visit buttons. In Adventureland, I do recommend the Tiki Room and Jingle Cruise - both different. New Orleans Square - you're going to love Pirates of the Caribbean and Haunted Mansion Holiday. Santa is all the way back in Critter Country if you want to see him. That is where you'll find Splash Mountain and Winnie the Pooh, which are both different. In Frontierland, Big Thunder Mountain Railroad is pretty much like the one at WDW Magic Kingdom, but it's so much fun! In Fantasyland, be sure to try Alice in Wonderland, Mr. Toad's Wild Ride, and the others if the lines let you. Personally, I think the Matterhorn is a must-do, even though it's bumpy. Remember that Tomorrowland side is a bit wilder than Fantasyland side. Tomorrowland also has the Finding Nemo Submarine attraction and if Autopia is open you might try it because it's different than the one at the Magic Kingdom WDW. The Mickey & the Magical Map show in Fantasyland is a nice place to unwind for a half hour and enjoy the show. Paint the Night and the fireworks are worth seeing. Try to find a spot somewhere on Main Street for Paint the Night (maybe 2nd show?), and if you can, make your way to a spot on Main Street for the fireworks. If not Main Street, you might try in front of It's a Small World. Also, if you can possibly see Fantasmic, grab fastpasses for one of the shows. So, if you go to Disneyland on two days, you have two nights to watch Fantasmic, the Paint the Night Parade, and the fireworks. I also love the Christmas Parade, but it's up to your family if they want to watch two parades at Disneyland.
Have you made Dining Reservations? If not, you might consider it for at least one meal a day.
California Adventure - First thing to do is get fastpasses for Radiator Springs Racers, unless you have early entry and can go on that attraction first thing. Then get fastpasses because you'll want to go on it again. Of course, you know about Aladdin, so get a fastpass for that and World of Color in the evening. The Little Mermaid and Monsters Inc attractions are fun to go on. Soaring Over California is the same as the one at Walt Disney World, but I like the queue here because of the nod to Aerospace. If you can, check out the either the Christmas Tree Lighting or make sure you are at Cars Land when they turn the lights on (I'm learning more towards Cars Land). Be sure to also see the Viva Navidad show. It's fun.
There is going to be a lot to see, and you're going to have so much fun!
