We went last week. It was me, DH, 7yo DD, and a 2yo DD.
My best advice on your 2yo:
1. If you're potty training, or if your 2yo is potty trained, expect to spend quite a bit of time in the bathroom. This was probably my worst part of our trip. Almost every time we'd get in line, within 5 minutes, she would blurt out, "I gotta go potty." It got to be really annoying when it felt like I saw more of Disneyland bathrooms than of Disneyland itself. lol I wish she hadn't been potty trained at that point. But what can you do.
2. Don't plan things out too much. I went with a complete itinerary of what I figured we'd do every day, what rides we'd ride, where we'd eat, etc. Totally went out the window within the first hour. She didn't want to go on certain rides. She didn't want to stand in long lines. The absolute worst was waiting for the Princess Fantasy Faire to open. It said it opened at 11am. Well, they finally let us in (just to stand in line again) at about 11:15. We ended up spending an hour and a half in line just to see 3 princesses. Our 7yo loved it. The 2yo did, too, but she was so tired and cranky at that point. This "tip" goes along with the next one...
3. Take time out to just sit and rest. We never went back to our hotel (we just left early each day), but every now and then, we'd just sit on a bench and take it all in. It gave the kids a chance to rest from rides/lines/shows/all the people, and just sit with us. One time we bought a Dole Whip and shared it in a quiet corner while the commotion seemed to pass us by. Another time we got some of those frozen lemonades and just had fun sharing those. At first, I will admit, I was kind of upset because I felt like we were missing it all. But, I think even I needed that 15-30 minute break from the business of a relaxing vacation!
4. Take advantage of times (if any) that your 2yo might fall asleep in the stroller. Ours did this every day - usually late afternoon. We took the time either to take our 7yo on rides that the 2yo didn't want to do or just spent the quiet time shopping.
Hopefully some of this helps.