Actually, Stephanie, both times you've mentioned are perfect for a visit to the Happiest Place on Earth, but if I had to choose one, I'd go with late November / Early December. Nothing quite compares to Christmas at the Disneyland Resort...it's EXTRA magical this time of year. During this time, you'll be able to experience Sleeping Beauty's Winter Castle, in which the iconic Sleeping Beauty Castle is adorned in thousands of twinkling and the turrets are covered in snow. During this Holiday season, you'll also be able to experience special Holiday fireworks displays, during which it will "snow" in Southern California and don't forget the Amazing one-of-a-kind Christmas Fantasy Parade which will make it's way down Main Street USA on select evenings.
As if that isn't reason enough, all of your favorite Disney Characters will be decked out in their "Holiday wear" and two popular attractions, Small World and Haunted Mansion will have received their special Holiday layovers. On top of all of this, the decorations will blow you away along with the 60 foot tall Christmas tree which will be situated in Town Square! And if a visit with Santa is in order, no need to worry... he visits with guests of all ages in Big Thunder Ranch.
As far as hotels, I must recommend the newly renovated
Disneyland Hotel. This luxury hotel has recently received the AAA 4-Star rating and is located steps from Downtown Disney. Read more about why I love Disneyland Hotel in this previous answer:
Disneyland Hotel
I'm all out of room, so please write back if I can provide further details for you! -Amanda F.